Thesis >> Literature Review
The Literature Review chapter in a thesis, which follows the Introduction, fundamentally situates the current study within the context of existing research on the topic, differentiates it from what has already been investigated about the topic and establishes its unique contribution to the field. This chapter allows the authors to demonstrate a thorough awareness of key issues that are relevant to the research topic and justify their inclusion as a member of the academic community in their discipline.
The Literature Review, which creates the theoretical foundation for the current study as it presents, analyses and evaluates the research discussed, fulfils multiple communicative purposes:
- Identifying the research topic and its main themes.
- Presenting the theoretical viewpoints, product or system designs, models and algorithms, to establish their relevance to the research topic.
- Reviewing and evaluating relevant research.
- Identifying the research gap that the thesis will address.
- Stating the contribution of the study.
The Literature Review chapter details the main themes of the research topic that is central to the PhD thesis. Depending on the nature of the study, it explains the theoretical perspectives that form the basis of the study, product or system designs, or models and algorithms to rationalize their selection and show how they are relevant. These perspectives are critically evaluated and synthesized to identify the research gap and create the context for he research gap that the thesis seeks to address. The Literature Review also makes explicit the significance of the research and its contribution to the field of study.
All these communicative purposes provide the reader with an in-depth understanding of the research and demonstrate the writer’s knowledge of the research topic to the examiners.
Activity 1
The following five extracts are from the Literature Review of six theses in the Engineering sub-disciplines. Read each extract and from the options that follow it, identify its relevant communicative function by placing a tick (✓) in the relevant box. Each extract only has one correct answer.
Click on the button ‘Check answer’ after each set of options to see the correct answer.
Note: […] indicates text has been edited due to space constraints.
Extract A
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In this chapter, the basic theory necessary for the physical understanding of relevant phenomena in RE- Doped amplifiers (REDOA) is presented. First, a brief review of Einstein’s treatment is introduced, describing the interaction of light and RE ions in the gain media. In addition, the Judd-Ofelt theory that was used to analyze the forced electric-dipole transitions within the configuration of RE ions is discussed in detail. Second, the optical waveguide theory is briefly introduced […]. Finally, the rate equation used to determine the population inversion of EDFA is discussed. |
| Adapted from: B. Chen, “Rare Earth Ions Doped Oxide Glass Materials”, Ph. D dissertation, Dept. of Elect. Eng., CITYU, Hong Kong, 2015. [Online] Available: CityU Institutional Repository. |
Identifying the research topic and its main themes.
Presenting the theoretical viewpoints, product or system designs, models and
algorithms, to establish their relevance to the research topic.
Reviewing and evaluating relevant research.
Identifying the research gap that the thesis will address.
Stating the contribution of the study.
Check
Extract B
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Unresolved anaphora, both nominal and pronominal, is a discourse-level problem. Orăsan (2007) and Steinberger et al. (2007) show that reliable anaphora resolution enhances summarization. But conflicting observations (Mitkov et al., 2007) exist. Salton et al. (1997), who utilized text structuring and segmentation, tested the possibility of using paragraphs, instead of sentences, as extraction units. A paragraph relationship graph is established for a text, based on which topic-bearing paragraphs can be identified and extracted with “bushy” or “depth-first” algorithms. A more comprehensive application-oriented endeavor is reported by Strzalkowski et al. (1999). |
| Adapted from: R. Zhang, “Coherence-targeted Text Summarization”. Ph. D dissertation, Dept. of Comput. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK Poly U Electronic Theses |
Identifying the research topic and its main themes.
Presenting the theoretical viewpoints, product or system designs, models and
algorithms, to establish their relevance to the research topic.
Reviewing and evaluating relevant research.
Identifying the research gap that the thesis will address.
Stating the contribution of the study.
Check
Extract C
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The review of literature shows that IDF is a type of flame which possesses the advantages of both premixed flame and diffusion flame. Although there are several research studies on IDF burning hydrocarbon fuels, there is limited research on IDF burning fuel mixture, especially for fuel mixture of LPG and H2. Also there is a lack of information on LPG and H2 fuel mixture. Therefore, it is necessary to carry out the present project to study the combustion, thermal and emission characteristics of IDF burning LPG and H2 mixture, and to provide comprehensive information on LPG-H2 IDF. |
| Adapted from: J. Miao, “Combustion, Thermal and Emission Characteristics of Gas-fired Inverse Diffusion Flames Burning mixed LPG-Hydrogen Fuel”, Ph. D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2015. [Online]. Available: HK PolyU Electronic Theses. |
Identifying the research topic and its main themes.
Presenting the theoretical viewpoints, product or system designs, models and
algorithms, to establish their relevance to the research topic.
Reviewing and evaluating relevant research.
Identifying the research gap that the thesis will address.
Stating the contribution of the study.
Check
Extract D
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In this thesis, we present a method that combines the EGFR-inhibitor inter-action pattern and the specific personal features for each of our 168 clinical subjects to construct a personalized drug resistance prediction model. Our method can have useful applications to the development of personalized medicine/therapy. |
| Adapted from: D. Wang, “Deciphering Inter-and Intra-molecular Interactions Based on the Dynamic and Structural Properties of Molecules”. Ph. D dissertation, Dept. of Electronic Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Identifying the research topic and its main themes.
Presenting the theoretical viewpoints, product or system designs, models and
algorithms, to establish their relevance to the research topic.
Reviewing and evaluating relevant research.
Identifying the research gap that the thesis will address.
Stating the contribution of the study.
Check
Extract E
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The environmental degradation of Atrazine (ATZ) generally follows three main pathways. The first pathway is the hydrolysis of the C−Cl bond, leading to the formation of hydroxy-atrazine, which is one of the main degradation products in both the soil and aquatic systems. The second pathway is dealkylation, but both the deethylated-ATZ and deisopropylated-ATZ are phytotoxic products. However, ATZ is significantly more toxic than its degradation products to many algae. The third degradation process corresponds to the splitting of the triazine ring usually caused by micro-organisms (Bintein and Devillers 1996). |
| Adapted from: L. Xu, “Degradation of Refractory Contaminants in Water by Chemical-Free Radicals Generated by Ultrasound and UV Radiation”, Ph. D dissertation, Dept. Civil and Env.. Eng., HKPOLYU, Hong Kong, 2014. [Online]. Available: HK PolyU Electronic Theses. |
Identifying the research topic and its main themes.
Presenting the theoretical viewpoints, product or system designs, models and algorithms, to establish their relevance to the research topic.
algorithms, to establish their relevance to the research topic.
Reviewing and evaluating relevant research.
Identifying the research gap that the thesis will address.
Stating the contribution of the study.
CheckMoves in the Literature Review
The Literature Review helps to establish the context for the study by critically evaluating key perspectives relevant to the research topic to show the research gap that existing research has still not addressed. In order to do so, the writer includes five key moves in the chapter:
- Identifying the research topic and its main themes.
- Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
- Reviewing and evaluating relevant research.
- Identifying the research gap.
- Stating the contribution of the study.
A Literature Review might not include all the moves listed above. For example, some writers do not make an explicit reference to the contribution of the study as they might have already covered it in the Introduction. On the other hand, some of the moves may appear more than once because the writer needs to present a number of relevant theoretical viewpoints.
Other possible moves include:
- Introductory statements which provide a brief overview of the focus and organisation of this chapter.
- Concluding statements which summarise the main points made in the chapter and which may also include a transition statement serving as a lead-in to the next chapter (Methods).
The following extracts from multiple theses in Engineering illustrate the five key moves. An explanation of the featured move follows after the extract. Click on the button ‘Explanation of move’ to see the move explained.
Note: […] indicates text has been edited due to space constraints.
Extract A
Identifying the research topic and areas of focus related to it
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In this chapter, topical research on the Photonic Crystal Fiber (PCF) will be reviewed. The basic concepts and properties and its classifications including index-guiding PCF, hollow-core PCF, high birefringence PCF and suspended-core fiber, as well as their sensing applications are introduced. The fundamental ideas and applications of Fiber Bragg Grating (FBG) fabricated in PCF are also reviewed. |
| Adapted from: Z. Liu. “Fabrication of Novel Optical Fibers and Their Sensing Applications” Ph. D dissertation, Dept. of Elect. Eng., HK Poly U, Hong Kong, 2015. [Online] Available: HK Poly U Electronic Theses. |
Extract B
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms
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Shallow-text based approaches make use of shallow text features, such as word frequency, length, position, text layout, keywords, etc., to find important units (usually sentences) for summaries. The summarization algorithms are usually heuristically or empirically guided. The earliest such approach is reported by Luhn (1958), who measures sentence summary-worthiness by word frequency only, assuming that the summary sentences must contain the most frequent words in a text. Edmundson (1969) extends Luhn’s work by considering cue phrases, title, and location […]. |
| Adapted from: R. Zhang, “Coherence-targeted Text Summarization”. Ph. D dissertation, Dept. of Comput. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK Poly U Electronic Theses. |
Extract C
Reviewing and evaluating relevant research
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In Bianchi’s landmark paper [33], an analytical model was proposed to […]. Based on the model, the throughput performance of saturated IEEE 802.11 DCF networks was further evaluated, and verified by simulation results. As a few properties of DCF were not considered in Bianchi’s original paper [33], the model was later extended by a number of research studies [34–47] to include more practical assumptions such as back off counter frozen [34,37,39], finite retransmissions [35,36], and unsaturated traffic scenarios [40–47]. Little consensus is, nevertheless, reached on the characterization of the network steady-state operating point in unsaturated scenarios due to differences in assumptions and models. |
| Adapted from: Y. Gao “From Heterogeneous IEEE 802.11 DCF Networks to IEEE 802.11e EDCA Networks: Modeling, Differentiation, Optimization and Quality-of-Service Guarantee”. Ph. D dissertation, Dept. of Arch. and Civil Eng., City U, Hong Kong, 2012. [Online] Available: City U Institutional Repository. |
Extract D
Identifying the research gap.
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There has been extensive activity focusing on the resource allocation problem in OFDMA relay networks. […]. Unfortunately, these studies only focus on the network efficiency and do not explicitly consider fairness. However, fairness is an important metric of performance when resource allocation is considered. As discussed in Section 2.2.4, the fairness issue over relay networks has indeed received some attention recently. However, the studies reviewed previously have not paid attention to flexible service-specific rate requirements of different users. |
| Adapted from Y. Shen, “Dynamic Resource Allocation and Optimization in Wireless Relay Networks”, Ph. D dissertation, Dept. of Mechanical and Biomedical Eng., CITYU, Hong Kong, 2012. [Online] Available: City U Institutional Repository. |
Extract E
Stating the contribution of the study
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Protein subcellular localization prediction is to determine the cellular compartment(s) that a protein will be transported to. […] However, the number of newly found protein sequences has been growing rapidly in the post-genomic era. Therefore, more reliable, efficient and automatic methods are highly required for the prediction of where a protein resides in a cell. The knowledge thus obtained can help biologists to use these newly discovered protein sequences for both basic biological research and drug design [14]. |
| Adapted from: S. Wan, “Protein Sub-cellular Localisation: Gene Ontology Based Machine Learning Approaches”, Ph. D dissertation, Dept. Elect and Inform. Eng., HKPOLYU, Hong Kong, 2014. [Online]. Available: HK Poly U Electronic Theses. |
Coherent organisation of information structures
A Literature Review covers vast and complex information. Organising this information in a logical and coherent manner is therefore crucial, as this allows readers to process the information easily. The following techniques help achieve this objective.
- Effective paragraph structure (topic sentences, development of controlling ideas*, elaboration, summary sentence)
- Logical connections between paragraphs (paragraph hooks)
- Effective headings and sub headings (clear, concise and specific headings)
* A controlling idea is part of the topic sentence in a paragraph, which is the main focus of the paragraph. It is elaborated and exemplified in the paragraph.
The following extract from a thesis in Electronic and Information Engineering illustrates these three strategies. Click on the numbers in superscript to see their explanation.
Note: […] indicates text has been edited due to space constraints.
Extract A
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[…] GO-based methods make use of biological knowledge about genes and gene products in the GO databases. GO-based methods can be viewed from the following two perspectives1. |
| Adapted from: S. Wan, “Protein Sub-cellular Localisation: Gene Ontology Based Machine Learning Approaches”, Ph. D dissertation, Dept. Elect and Inform. Eng., HKPOLYU, Hong Kong, 2014. [Online]. Available: HK PolyU Electronic Theses. |
Activity 1>> 2>> 3
The following extracts are from the body section of the Literature Review from different theses. From the options that follow each extract, select the move that the extract illustrates. Each extract only illustrates one move.
Click on the ‘check answer’ button to see the move illustrated in the extract.
Note: […] indicates text has been edited due to space constraints.
Extract A
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The key of the analysis of heterogeneous networks lies in the characterization of the network steady-state operating point, which, intuitively, should be determined by […]. […] Approximate approaches have been developed in [61–63] to search for the optimal backoff window sizes to maximise the network throughput in the saturated scenario. Yet good accuracy was demonstrated only when the number of nodes is small [62]. How to optimise the network throughput performance of heterogeneous IEEE 802.11 DCF networks remains largely unknown. |
| Adapted from Y. Gao. “From Heterogeneous IEEE 802.11 DCF Networks to IEEE 802.11e EDCA Networks: Modeling, Differentiation, Optimization and Quality-of-Service Guarantee”, Ph. D dissertation, Dept. of Elect. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Identifying the research topic and its main themes.
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
Reviewing and evaluating relevant research.
Stating the contribution of the study.
Check
Extract B
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Most works, however, treat coherence as a self-evident quality of summary. Little thought has been given to the multi-faceted nature of coherence and its implications for developing models and algorithms of summarisation. In contrast, this research views coherence as an analyzable concept and a key player in the whole process of summarisation. Subject to different interpretations, coherence has different implications for developing summarisation models. This work proves that formulating coherence as such is beneficial for improving the state of the art and for breaking new fertile ground of text summarization. |
| Adapted from: R. Zhang, “Coherence-targeted Text Summarization”. Ph. D dissertation, Dept. of Comput. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK Poly U Electronic Theses. |
Identifying the research topic and its main themes.
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
Reviewing and evaluating relevant research.
Identifying the research gap.
Stating the contribution of the study.
Check
Extract C
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Protein-protein interactions (PPIs) [82, 125, 142] regulate many processes in living cells and play a fundamental role in many diseases […]. Studies of PPIs are mainly from the biochemical [41, 53, 172] and computational [144, 151, 170] perspectives. As noted above, the dynamics of molecules or molecular systems are vital for uncovering molecular activities, and normal mode analysis (NMA) [6, 7, 72, 109], is an efficient tool to reveal the collective motions of molecular systems, especially for large complexes of multiple components. |
| Adapted from: D. Wang, “Deciphering Inter-and Intra-molecular Interactions Based on the Dynamic and Structural Properties of Molecules”. Ph. D dissertation, Dept. of Electronic Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Identifying the research topic and its main themes.
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
Reviewing and evaluating relevant research.
Identifying the research gap.
Stating the contribution of the study.
Check
Extract D
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Compared to sequence-based methods, GO-based methods are found to be superior [64, 72, 73, 102]. However, existing GO-based methods are not without disadvantages and limitations. […]From the perspectives of GO terms extraction, as examined in Section 2.2.1, methods using InterProScan to retrieve GO terms can only produce a limited number of GO terms, which are not sufficient for accurate prediction. |
| Adapted from: S. Wan, “Protein Sub-cellular Localisation: Gene Ontology Based Machine Learning Approaches”, Ph. D dissertation, Dept. Elect and Inform. Eng., HKPOLYU, Hong Kong, 2014. [Online]. Available: HKPolyU Electronic Theses. |
Identifying the research topic and its main themes.
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
Reviewing and evaluating relevant research.
Identifying the research gap.
Stating the contribution of the study.
Check
Extract E
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The study of LPG-H2 IDF requires fundamental knowledge of many different topics. As IDF is a partially premixed flame, it is necessary to understand the basic information of both premixed flame and normal diffusion flame. The combustion characteristics of the three fuels (propane, butane and hydrogen) are also fundamental information necessary for the present study. Experimental investigations involved in this study include laminar burning velocity measurement, flame stability range test, flame length measurement, inflame OH-PLIF diagnose, flame temperature measurement and pollutant emission examination. Previous research in these areas is reviewed and analysed to provide a solid foundation for the present research project. |
| Adapted from: J. Miao. “Combustion, Thermal and Emission Characteristics of Gas-fired Inverse Diffusion Flames Burning mixed LPG-Hydrogen Fuel”. PhD dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong2015. [Online] Available: HK PolyU Electronic Theses. |
Identifying the research topic and its main themes.
Presenting relevant theoretical viewpoints, product or system designs, models and algorithms.
Reviewing and evaluating relevant research.
Identifying the research gap.
Stating the contribution of the study.
CheckThe following paragraphs are from a thesis in Electronic Engineering. Paragraph A (in italics) presents background information. Read it to contextualise the information in Paragraph B.
Sentences in Paragraph B are not in sequence and do not form a coherent unit of information. Re-order them by dragging each sentence into the table that follows the extract. One of them has been done for you.
Note: […] indicates text has been edited due to space constraints.
Paragraph A
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Non-small-cell lung carcinoma (NSCLC) has become a major threat to human health [114]. […] In clinical treatments of NSCLC, tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib are widely used [75, 199]. These two reversible inhibitors show stronger binding affinity with kinase mutants than the wild-type (WT) EGFR, and they indeed produce good results for many patients for a period of time [196]. |
| Paragraph B |
The cause of drug resistance is thought to be steric interference with the binding of inhibitors caused by the mutations [92, 98, 133]. However, the effectiveness of TKI inhibitors is limited by the emergence of drug resistance, sometimes due to a second mutation, such as the substitution of threonine with methionine at residue site 790 [196, 199]. Therefore, the EGFR mutation induced drug resistance leads to an urgent demand to develop new treatment strategies [26, 69]. However, the EGFR structure will be chemically modified via a covalent bond [196], which is not encouraged in practical therapy. |
| Adapted from: D. Wang, “Deciphering Inter-and Intra-molecular Interactions Based on the Dynamic and Structural Properties of Molecules”. Ph. D Dissertation, Dept. of Electronic Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
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Please click on the number in the table to see the explanatory notes.
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1. However, the effectiveness of TKI inhibitors is limited by the emergence of drug resistance, sometimes due to a second mutation, such as the substitution of threonine with methionine at residue site 790 [196, 199]. |
| Adapted from: D. Wang, “Deciphering Inter-and Intra-molecular Interactions Based on the Dynamic and Structural Properties of Molecules”. Ph. D Dissertation, Dept. of Electronic Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
The following extract is from a thesis in Civil and Environmental Engineering.
Read the extract and answer each of the following questions by colouring the section of the extract that includes its answer in the same colour as the question.
Note: […] indicates text has been edited due to space constraints.
- What is the ‘controlling idea’ in the topic sentence for Paragraph 1?
- Identify the sentence that elaborates the controlling idea in Paragraph 1.
- Identify the paragraph hook that links Paragraph 1 to Paragraph 2.
- What is the ‘controlling idea’ in the topic sentence for Paragraph 2?
- In Paragraph 2, identify the sentence that elaborates the controlling idea.
- In Paragraph 2, which sentence does the summary sentence of the paragraph link to?
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Please click on the the Questions to see the explanatory notes. Q1. What is the ‘controlling idea’ in the topic sentence for Paragraph 1?
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This section reviews common language features characteristic of the Literature Review, using extracts from theses in the Engineering sub-disciplines.
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Common language features in a Literature Review |
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Strategies for reviewing literature: comparing, contrasting and evaluating perspectives; hedging. |
Strategies for reviewing literature
A Literature Review draws together research perspectives to present an analysis and evaluation of existing work relevant to the research topic, to differentiate what has been researched from what has not yet been studied. It establishes how the current study will address the research gap and contribute to existing knowledge. This section examines three key linguistic strategies in achieving these objectives:
- The use of language of comparison and contrast to draw out similarities and differences in perspectives.
- The use of evaluative language to present a critical review of perspectives.
- The use of tentative expressions (hedging) to soften criticism of others’ work, or to present possible solutions.
Language of comparison and contrast
An effective Literature Review compares or contrasts perspectives to draw out their similarities and differences to synthesise existing perspectives and to develop the theoretical arguments that contribute towards addressing the research gap.
Below are a few examples of comparison-contrast structures from a Systems Engineering and Engineering Management thesis. Click on the numbers in superscript to see their explanations.
| Extract A |
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The COE method measures the change of MSE after deleting the input variable of interest from the original ANN. This technique is analogous to1 the stepwise method of identifying independent variables in MLR. Alternatively2, sensitivity analysis works by varying each input variable over either the entire or a partial range of possible values while3 holding all other input variables constant at a specified percentile […]. Sung [170] compared COE and sensitivity analysis in a real engineering problem, and found that both methods generated comparable results.4 Thus far, consensus has not been reached on which group of methods outperforms5 the other [82, 141]. |
| Adapted from: M. Xu, “Operations Improvement Systems for Hospital Emergency Department”, Ph. D dissertation, Dept. of Systems Eng. and Eng. Mgmt., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Language of evaluation
Existing research featured in a Literature Review is cited with a specific objective which is to compare perspectives to review and critically evaluate them. Evaluative language is used to reflect the writer’s views of other researchers’ work and rationalise their selection for the chapter. Such language allows the writer to provide a context for their approach to addressing the research gap.
The following extract from a Mechanical Engineering thesis illustrates the use of evaluative language used to evaluate a process (rapid mixing and Coriolis force based mixing), the literature on micromixers (existing research), a product (the passive micromixer, the CM mixing device).
Click on the numbers in superscript to see their explanations.
Note: […] indicates text has been edited due to space constraints.
| Extract B |
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Rapid mixing plays an important1 role in microfluidic applications for biochemistry analysis [80]. […]. Comprehensive2 reviews on various micromixers can be found in the literature [81-83]. Depending on […], the micromixers can be categorized into either active or passive type [90]. The passive micromixer is more attractive, due to the simple3 concept and relative convenience4 in design, fabrication and implementation. […] Compared with other mixing mechanisms, the centrifugal microfluidics (CM) mixing device does not need complicated design and costly53-D structure, and the Coriolis force based mixing is simple6to implement [54], therefore it has attracted increasing attention7 recently. |
| Adapted from: R. Yong. “Centrifugal Microfluidic Flow and Mixing with Applications in Cell Culture and Cell Lysing”. Ph D dissertation, Dept. Mech. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK PolyU Electronic Theses. |
Use of hedging in evaluation
While reviewing existing research, writers tend to use evaluative language to express their views. Notwithstanding the strength of the writer’s perspectives, writers often use cautious language to hedge and soften their criticism of other researchers’ work. This technique of hedging is also used when highlighting the research gap and making cautious claims in regard to the writer’s proposed approach. Commonly used language items used to hedge claims are:
- hedging verbs
- modals (verbs, adverbs, nouns and adjectives)
- adverbs of concession
- adverbs of frequency
In the following, the use of different hedging devices is illustrated with examples from theses in Engineering.
| Hedging verbs The use of hedging verbs, such as ‘appear’, ‘suggest’ and ‘seem’, is one technique to soften criticism of others’ work. |
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The flow softening type of the stress- strain behavior with an initial peak stress or oscillations suggests dynamic recrystallization*. |
| * Adapted from: D. Chalasani. “Hot Deformation and Microstructural Characteristics of Al and Si Containing Mg – Sn – 2Ca (TX 32) Alloys: Correlation with Processing Maps”. Ph. D dissertation, Dept. of Mech. and Biomed. Eng., CITYU, Hong Kong, 2013. [Online] Available: CityU Institutional Repository. ** Adapted from: R. Yong. “Centrifugal Microfluidic Flow and Mixing with Applications in Cell Culture and Cell Lysing”. Ph D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2012. [Online] Available: HK PolyU Electronic Theses. |
| Modal verbs These hedging devices are used to suggest varying degrees of possibility or certainty. use of hedging verbs, such as ‘appear’, ‘suggest’ and ‘seem’, is one technique to soften criticism of others’ work. |
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Compared to REDOA, OPA offers a wide gain bandwidth and may be tailored to operate at any wavelength*. |
| * Adapted from: B. Chen, “Rare Earth Ions Doped Oxide Glass Materials”, Ph. D dissertation, Dept. of Elect. Eng., CITYU, Hong Kong, 2015. [Online] Available: CityU Institutional Repository. ** Adapted from: R. Yong. “Centrifugal Microfluidic Flow and Mixing with Applications in Cell Culture and Cell Lysing”. Ph D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2012. [Online] Available: HK PolyU Electronic Theses. |
| Modal adverbs |
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Therefore, they concluded that the variability of strain in the experiment probably resulted from the variability of adhesive thickness during the wet lay-up wrapping. * |
| * Adapted from: J. Jiang, “Plasticity Modeling and Experimental Study of Fiber-enforced Polymer (FRP) –Confined Concrete columns”, Ph. D dissertation, Dept. of Civil and Arch. Eng., CITYU, Hong Kong, 2012. [Online] Available: CityU Institutional Repository. ** Adapted from: J. Miao, “Combustion, Thermal and Emission Characteristics of Gas-fired Inverse Diffusion Flames Burning mixed LPG-Hydrogen Fuel”, Ph. D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2015. [Online]. Available: HK PolyU Electronic Theses. |
| Modal nouns |
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For flames highly affected by force diffusion and buoyancy effect, such as IDF, of which the fuel flow is controlled by entrainment force provided by the central air jet, there is a possibility that fuels with very different densities, such as propane and hydrogen, may separate and burn in different locations in the flame. * |
| * Adapted from: J. Miao, “Combustion, Thermal and Emission Characteristics of Gas-fired Inverse Diffusion Flames Burning mixed LPG-Hydrogen Fuel”, Ph. D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2015. [Online]. Available: HK PolyU Electronic Theses. |
| Modal adjectives |
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Drawing on previous works on ordering for summarization and linguistic accounts of coherence, factors that can possibly enhance coherence: topic continuity and document date information are also considered. According to the event structure (3.3.1), all entity information is included in events and entity-based topic continuity possibly affects overall textual coherence. |
| Adapted from: R. Zhang, “Coherence-targeted Text Summarization”. Ph. D dissertation, Dept. of Comput. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK Poly U Electronic Theses. |
| Adverbs of frequency |
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Although it was found that the correlation of soil properties generally follows the fractal model in nature (Fenton 1999b), the finite-scale model is commonly applied in geotechnical analysis (e.g., Lumb 1974, Phoon et al. 2003, Cao 2012). |
| Adapted from: K. Huang, “Baynesian Inverse Analysis in Geotechnical Site Characterisation”. Ph. D dissertation, Dept. of Civil and Arch. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
| Adverbs of concession Another hedging technique is to balance one’s negative evaluation by preceding it with a positive evaluation. This is achieved by adverbs of concession such as ‘although’ and ‘despite’ which are followed by a positive comment about an aspect of the research, and then by a negative evaluation of aspects of the research topic that need to be addressed. |
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Although the weighted networks of like contain more information than unweighted networks, not all the information is helpful for community detection.* |
| * Adapted from: W. Fan. “Community Structure and its Applications in Online Social Networks”. Ph. D dissertation, Dept. of Elect. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. ** Adapted from: R. Yong. “Centrifugal Microfluidic Flow and Mixing with Applications in Cell Culture and Cell Lysing”. Ph D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2012. [Online] Available: HK PolyU Electronic Theses. |
Maintaining idea flow: Given-new information
A well-organised Literature Review requires attention to maintaining effective idea flow, such that one’s position and the presentation of complex arguments is communicated efficiently and precisely. In general, known or familiar information is presented first, followed by unknown or new information. This transition from given to new information makes the text more cohesive by linking complex ideas and assisting understanding.
The extract below from a thesis in Civil and Architectural Engineering illustrates how ‘new’ information in a sentence becomes the ‘given’ information for the next sentence, making it easier to process the complex information presented about the spatial correlation between the values of soil properties.
Click on the numbers in superscript in the text to see the explanation for the arrangement of ‘given’ and ‘new’ information.
Key: given new
| Extract A |
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The spatial correlation between the values of soil properties at different locations is modeled using a correlation function1. In general, the correlation function is categorized into the finite-scale model and the fractal model2. In the finite-scale model, the correlation dies out rapidly as the separate distance increases to the correlation length while it remains strong over a very large distance for the fractal model3 (Fenton 1999a, Cao 2012). Although it was found that the correlation of soil properties4 generally follows the fractal model in nature (Fenton 1999b), the finite-scale model is commonly applied in geotechnical analysis5 (e.g., Lumb 1974, Phoon et al. 2003, Cao 2012). The major advantages of the finite-scale model6are that a single parameter of correlation length can capture the whole information on spatial correlation and little difference arises between these two types of models over a finite domain7 (Fenton 1999b). |
| Adapted from: K. Huang, “Baynesian Inverse Analysis in Geotechnical Site Characterisation”. Ph. D dissertation, Dept. of Civil and Arch. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Verb tenses
In a Literature Review, when referring to source texts, the present simple, the simple past and the present perfect are commonly used. The writer’s choice of tense is determined by the communicative objective they wish to achieve.
a) Referring to another researcher’s actions
The simple past is used to describe actions which, at the time of writing, had already been completed in studies being referred to.
| Extract A |
|
Fazel et al. (2011) applied the Comprehensive Sensing theory to count and localize targets in wireless sensor networks. |
| Adapted from: R. Xie. “Algorithm Optimization in Wireless Sensor Networks and Data Center Networks”. Ph. D dissertation, Dept. of Comp. Sci., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
| Extract B |
|
Fazel et al. (2011) apply the Comprehensive Sensing theory to count and localize targets in wireless sensor networks. |
| Adapted from: R. Xie. “Algorithm Optimization in Wireless Sensor Networks and Data Center Networks”. Ph. D dissertation, Dept. of Comp. Sci., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
In Extract A, the past tense is correctly used as the writer is reporting on what was done in previous research. Using the present tense to refer to what was done (as in Extract B), would incorrectly imply that the CS theory is applied on a regular basis rather than during the time when the research was carried out.
b) Referring to another researcher’s statements (what they said/wrote)
When referring to what another researcher said or wrote, and not what they did in their research, either the present tense or the past simple tense can be used. If one views the information in the paper one has read as a completed event one is reporting, the past tense can be used. However, if one views the paper as a source of information that will hold true even in the future, the present tense can be used.
The example in Extract A can be presented using either tense, as one is referring to the researchers’ statements (‘point out’), and not their actions (‘applied’). As shown in Extracts C and D below, the example in Extract A can be presented using either tense, as one is referring to the researchers’ statements (‘point out’), and not their actions (‘applied’).”
| Extract C |
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Fazel et al (2011) point out that the CS theory can be applied to count and localize targets in wireless sensor networks (Present tense). |
| Extract D |
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Fazel et al. (2011) pointed out that the CS theory could be applied to count and localize targets in wireless sensor networks (Past tense, the modal ’can’ is changed to ‘could’ as the action is being reported on). |
c) Informing the reader about the state of a debate in the field
The present tense is used to describe a debate which is still without agreement or consensus, as shown in Extract E.
| Extract E |
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The differences in assumptions and approximations, make it difficult to arrive at a consensus. |
| Adapted from Y. Gao. “From Heterogeneous IEEE 802.11 DCF Networks to IEEE 802.11e EDCA Networks: Modeling, Differentiation, Optimization and Quality-of-Service Guarantee.”. Ph. D dissertation, Dept. of Elect. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
The past tense is used to describe a controversial issue that was debated in the past but now, is no longer current. The following extract has been adapted to reflect an outdated controversy.
| Extract F |
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For example, the validation of current selections of the gradient wind height in many wind codes was highly questioned (Irwin, 2009), and the specification of design wind speeds for tall buildings in Hong Kong was debated in the wind engineering community because of the uncertainties involved in the ratio of surface to upper-level wind speeds during typhoons (Pande et al., 2002). |
| Adapted from Y. He. “Boundary layer wind characteristics and wind-induced dynamic responses of a super-tall building”. Ph. D dissertation, Dept. of Arch and Civil. Eng., CITYU, Hong Kong, 2013. [Online] Available: CityU Institutional Repository. |
d) Referring to a field of study
In the earlier sections of the Literature Review, a general introduction to the broad area of study is presented to create a background of relevant knowledge that is current up to the present time and links past research to current studies. The present perfect tense is used to achieve this objective and show that the area of study is currently relevant. This approach is exemplified in the following extract.
Note: […] indicates text has been edited due to space constraints.
| Extract G |
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Cu precipitation strengthening in steels has attracted considerable attention and has become the cornerstone for the development of high strength, low carbon steels [43,46,54-59]. […] It is known that precipitation strengthening is strongly dependent on the precipitate size, number density, and distribution. |
| Adapted from Z. Jiao, “Alloy Design, Characterization, and Mechanical Properties of Advanced Ultra-high Strength Steels Strengthened by Nano-precipitates”, Ph. D dissertation, Dept. of Mech. And Bio Med. Eng., CITYU, Hong Kong, 2014. [Online] Available: CityU Institutional Repository. |
Reporting verbs
Reporting verbs help the writer signal their evaluation of another researcher’s work. They can either be neutral, tentative and strong. The following table includes extracts from Engineering theses to illustrate each category. Click on the box ‘Explanation of example’.
Note: […] indicates text has been edited due to space constraints.
| Table 1: Reporting verbs used in Engineering theses | |
|
Category of reporting verb |
Examples from Engineering thesis |
|
Neutral verbs |
Dong et al. (2007), Zhen et al. (2012) and Sze et al. (2006) observed flame colors of IDFs burning butane and LPG, and suggested that flame luminosity is a signal of soot distribution*. |
|
Tentative verbs |
Bisby and Take (2009) recommended the optical measurement method over strain gauging, as the measurements from discrete and sparse points would result in an inconsistent efficiency factor. ** |
|
Strong verbs |
Yang et al. (2002) investigated […]. They concluded that the strength was affected by fiber misalignment more significantly than the elastic modulus. ** |
| * J. Miao Adapted from: J. Miao, “Combustion, Thermal and Emission Characteristics of Gas-fired Inverse Diffusion Flames Burning mixed LPG-Hydrogen Fuel”, Ph. D dissertation, Dept. of Mech. Eng., HKPOLYU, Hong Kong, 2015. [Online]. Available: HK PolyU Electronic Theses. ** Adapted from: J. Jiang, “Plasticity Modeling and Experimental Study of Fiber-enforced Polymer (FRP) –Confined Concrete columns”, Ph. D dissertation, Dept. of Civil and Arch. Eng., CITYU, Hong Kong, 2012. [Online] Available: CityU Institutional Repository. |
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Activity 1>> 2>> 3
The following extracts are from the Literature Review of a thesis in Mechanical Engineering. Using the colour palette below, identify the following language features in the extracts.
Note: […] indicates text has been edited due to space constraints.
- Language of comparison and contrast
- Evaluative language
- Hedging
erase
erase
erase
erase
erase
erase
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In the following gap-fill exercise, the verbs used have been deleted. Complete the blank with the correct option from the drag and drop options below.
Click on the alphabet identifiers A- H to read the explanation for each answer.
| Options for deleted reporting verbs | |
| (A) | demonstrate demonstrated have been demonstrated |
| (B) | remaining Remain remained |
| (C) | have formed formed Form |
| (D) | Presents presented have been presented |
| (E) | Was were are |
| (F) | is Was are |
| (G) | reduce reduced has been reduced |
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- Have been demonstrated. The past perfect tense is needed here as the background information on efficient mixing on a CM platform up to the present time is outlined.
- Remain. The present tense is required here as the author is stating a fact about the unresolved issues regarding batch mixing.
- Form. The present tense is used to make a factual statement about the author’s research.
- Presented. “Presented” is used here because of contracted relative clause (“which are presented”).
- Are. The present tense is used to state a fact about ‘the quantitative results of aspect ratio and rotation speed of the microchannel on mixing’. ‘Are’ agrees with ‘results’.
- Are. The present tense is used to state a fact about the three processes – that they are not known and hence require to be established by trial and error.
- Has been reduced. The present perfect passive is required as it refers to alternative procedures (additional innovative configurations) over the years up to the present time.
Note: […] indicates text has been edited due to space constraints.
Reporting verbs have been deleted in the following extract. From the available options below, select the most appropriate one to complete the text.
Click on the button ‘Check answers’ after Extract F to see the answer key.
Click alphabet identifier (A- F) to read the explanation for each answer.
| Options for deleted reporting verbs | |
| (A) | comment explored believe |
| (B) | investigated described recommended |
| (C) | used extended proposed |
| (D) | show evaluated measured |
| (E) | disagree proposed investigated |
| (F) | discuss contradict measure |
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Based on previous studies on lexical relations (Morris and Hirst,1991), Barzilay and Elhadad (1997) explored summarization using lexical chains, a useful tool to measure the connectedness between sentences with reference to lexical relations. […]. Teufel and Moens (1999) investigated discourse-level summarization by studying the “argumentative structure” of science research papers. They identified 7 rhetorical roles […]. Similarly, Blair-Goldensohn and McKeown (2006) used “rhetorical-semantic” relation (Contrast and Cause) to generate query-focused summaries. […]. Orăsan (2007) and Steinberger et al. (2007) show that reliable anaphora resolution enhances summarization. However, Mitkov et al., 2007 disagree and present conflicting observations […]. The PALSUMM (Polanyi et al., 2004) introduced in 1.1.4 is an implemented system that works on the syntactic and semantic structure of the discourse. Thione et al. (2004) discuss the discourse-level syntactic structure used in it, such as coordination, subordination and n-summaries. |
| Adapted from: R. Zhang, “Coherence-targeted Text Summarization”. Ph. D dissertation, Dept. of Comput. Eng., HKPOLYU, Hong Kong, 2012. [Online]. Available: HK PolyU Electronic Theses. |
Please click on the alphabet identifiers A-F to see the explanatory notes.
|
believe |
explored |
comment |
|
|
investigated |
described |
recommended |
|
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extended |
used |
proposed |
|
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show |
evaluated |
measured |
|
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disagree |
proposed |
investigated |
|
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contradict |
discuss |
measure |
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