Literature Reviews and Source Materials, Explained

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Literature Reviews and Source Materials

Research Methods in Psychology · Chapter 3: Research Design and Methodological PlanningSection 3.5 · lesson 20 of 9410 min · free with a free account

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In this lesson

Searching, evaluating, and synthesizing the existing body of psychological research.

  • Explain what a literature review is for
  • Distinguish narrative, systematic and meta-analytic reviews
  • Apply a six-step systematic search strategy
  • Evaluate source quality and avoid plagiarism

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Everything said in the video, section by section (1,509 words). Read along, or search it.

Research Design and Methodological Planning

Literature Reviews and Sources

No research study exists in isolation. Every investigation builds on work that came before it, whether the author admits that or not. The literature review is where you make that debt explicit, and useful. It is also the part of a project students most often treat as a formality. That is a mistake, and this section is about why. By the end you will explain what a review is actually for. You will distinguish a narrative review, a systematic review, and a meta-analysis. You will run a six step search strategy, from search terms through to synthesis. You will judge whether a source deserves the weight you want to put on it. And you will recognize four kinds of plagiarism, including the two that catch honest students.

Why Reviews Matter

No Study Exists in Isolation

Start with what a literature review is for. It establishes what is already known in the field. It identifies gaps and inconsistencies in that existing knowledge. And it justifies the rationale for the new study you want to run. Those are three separate jobs, and the third one depends on the first two. A rigorous review is not a summary of everything published on a topic. It is a critical, analytical synthesis. A coherent argument about the state of the field. What has been established, what remains contested, and what your study will contribute. Skip it, and three things go wrong. You duplicate work already done, you miss the methodological lessons of prior studies, or your findings float free of the debates that give them meaning.

Three Kinds Of Review

Narrative, Systematic, Meta-Analytic

There are three broad kinds of review, and they are not interchangeable. The first is the narrative review. It gives a broad, qualitative synthesis of the literature. The reviewer selects studies, summarizes them, identifies themes, and draws conclusions. It is flexible, and it can cover a wide range of topics. But notice who is doing the selecting. Narrative reviews are susceptible to selection bias. The reviewer's own theoretical commitments may influence which studies get included. The second is the systematic review, which follows a pre-specified, transparent protocol. The third is meta-analysis, which statistically combines the results of multiple studies. It produces a pooled estimate of the effect size across all of them.

Protocol And Pooling

What Rigor Adds

Look more closely at what the extra rigor buys you. A systematic review uses explicit inclusion and exclusion criteria. Comprehensive database searches, and formal quality assessment tools. The point of all that machinery is to minimize bias and ensure reproducibility. Which is why systematic reviews are the gold standard for a specific, well-defined question. Meta-analysis goes one step further and pools the numbers themselves. It increases statistical power, because you are working with more data than any single study had. And it allows analysis of moderating variables. Those are factors that might explain why effect sizes differ from one study to the next. Now the practical point. None of the three is simply better than the others. A systematic protocol answers a narrow question well, and a narrative review is what you want when introducing a topic.

Matching Type To Task

Which Review, and When

So match the review type to the task in front of you. A narrative review is broad, flexible, and qualitative, with studies chosen by the reviewer. Use it when introducing a new topic, or providing theoretical context. A systematic review has a pre-specified protocol, a comprehensive search, and is reproducible. Use it when you are answering a specific, well-defined empirical question. A meta-analysis pools results statistically, estimates effect size, and analyzes moderators. Use it when you want to quantify the magnitude of an effect across many studies. Read those three rows as a question about your own aim. Are you orienting a reader, settling a question, or measuring a size? Each aim has a review type that fits it, and two that do not.

Building The Search

Systematic Search, Steps 1 to 3

Now the search itself, in six steps. Step one is to define your search terms. Identify the key concepts in your research question, and then generate synonyms for each one. Depression might also be searched as depressive disorder. Or as major depressive episode, or simply as low mood. A search is only as good as its vocabulary. One term quietly misses every study that used a different name for the same construct. Step two is to select your databases, and to use more than one. For psychology, that means PsycINFO, PubMed, Web of Science, SCOPUS, and Google Scholar. Step three is to apply inclusion and exclusion criteria, specified in advance. Peer-reviewed, published in English, within the last ten years, for example.

Results To Argument

Systematic Search, Steps 4 to 6

Step four is to screen the results you got back. Review titles and abstracts, to identify studies that look potentially relevant. Then retrieve the full texts for whatever passes that initial screen. Step five is extraction, and this is the step people skip. For every study, record the authors, the year, and the design. The sample, the measures, the findings, and your quality assessment. Step six is to synthesize and evaluate. Organize the studies thematically, rather than one after another. Identify agreements, contradictions, and gaps, and evaluate the quality of the evidence. Without a structured record of each study, that synthesis becomes a list of impressions. Impressions cannot be checked, and an argument has to be checkable.

Judging A Source

Six Criteria for Source Quality

Not every published paper deserves equal weight. Six criteria decide how much a source can carry. Peer review, sample quality, and measurement validity. Design appropriateness, statistical rigor, and transparency. Treat them as a set rather than a checklist. A paper can pass peer review and still use a measure that is invalid for your construct. It can have a large sample and a design that cannot support the conclusion it draws. Each criterion catches a different way a source can fail you. And a source that fails one of them is not worthless. It simply cannot carry the specific weight you wanted to put on it.

Six Questions

What Each Criterion Asks

Peer review asks whether independent experts reviewed the article before publication. Peer-reviewed journal articles are the gold standard here. Sample quality asks whether the sample is adequate and representative. And whether inclusion and exclusion criteria are clearly stated. Measurement validity asks whether the measures are reliable and valid for the constructs studied. Design appropriateness asks whether the design actually matches the research question. And whether the stated conclusions can be supported by that design. Statistical rigor asks whether the analyses suit the data. And whether effect sizes are reported alongside p values, rather than instead of them. Transparency asks whether the methods are described in enough detail to allow replication. Note the limit of the first criterion. Clearing peer review means a source cleared a bar. It does not mean the study answers your question well.

Attribution

Plagiarism Comes in Four Forms

Now the part with real consequences attached. Academic integrity requires that all ideas, findings, and words taken from other sources be attributed. Plagiarism is presenting another person's work as your own, and it is a serious form of academic misconduct. And it comes in four forms, only one of which looks like copying. Direct plagiarism is copying text verbatim without quotation marks or citation. The fix is simple. Use quotation marks for verbatim text, and cite the source. Paraphrase plagiarism is restating a source's ideas in slightly different words, without citing. So cite even when you paraphrase, and make sure the restatement is genuinely your own. Mosaic plagiarism blends phrases from a source with your own text, without attribution. Keep notes that clearly separate your ideas from source material, and that one cannot happen. Self-plagiarism is resubmitting previously submitted work without disclosure. Disclose prior use of your own work, and ask your supervisor for guidance.

Writing It Up

The Shape of a Critical Review

Finally, the shape of the thing you write. A well-written literature review is a critical, analytical argument. It demonstrates wide reading, careful evaluation of sources, and genuine synthesis. Five parts do that work. The introduction defines the scope of the review, and explains why the topic is important. Then organization, and this is where most drafts fail. Group studies by theme, by theory, or by methodology. Do not simply list them in sequence, one paragraph per paper. Critical evaluation comes next. For each major finding, evaluate the supporting evidence. Then identify gaps, explicitly, because that is what justifies your own study. And the conclusion summarizes the state of the field, linking those gaps to your research question. Read it back and ask one question. Does this argue, or does it merely list?

Putting It Together

Summary, and One Test Case

A rigorous review does three things. It establishes the existing state of knowledge. It identifies gaps that justify new investigation. And it situates your study within its theoretical context. Getting there takes structured searching, critical evaluation, synthesis, and strict citation practice. Now test yourself on one. A student finds thirty studies supporting their hypothesis, and five that contradict it. They include only the supporting studies in their review. Name the problems before you hear the answer. Methodologically, the review is no longer a description of the field. It is selection bias made deliberate, and any gap it claims to find is manufactured. Ethically, it misrepresents the state of the evidence to every reader who trusts it.

About Research Methods in Psychology at UPI Study

Research Methods in Psychology (Psychology 111) is a self-paced online course of 94 video lessons in 16 chapters, from the scientific method and research ethics to designs, data collection, sampling, measurement, validity, experiments, descriptive statistics and hypothesis testing. It carries a NCCRS credit recommendation for 3 semester credits.

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How psychologists know what they knowResearch Methods in Psychology teaches how psychological studies are designed, run and judged: research ethics, surveys and observation, correlational and experimental designs, sampling, reliability and validity, and the statistics used to test hypotheses. It is a core course in psychology and many social-science degrees.
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Universities that work with NCCRS

Research Methods in Psychology carries a NCCRS credit recommendation. These universities work with NCCRS; some are UPI Study's signed partners. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.

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FAQ

Questions students ask us

About Literature Reviews and Source Materials

What is the difference between a narrative review, a systematic review and a meta-analysis?
A narrative review is a broad, flexible, qualitative synthesis in which the reviewer chooses the studies, so it is open to selection bias. A systematic review follows a pre-specified protocol with explicit inclusion criteria, comprehensive searches and quality assessment, making it reproducible. A meta-analysis statistically combines results from multiple studies to estimate a pooled effect size and can test moderators that explain why effects differ between studies.
How do you search the literature for a psychology research project?
A structured search has six steps: define search terms and their synonyms, search several databases such as PsycINFO, PubMed, Web of Science, Scopus and Google Scholar, apply inclusion and exclusion criteria set in advance, screen titles and abstracts before reading full texts, extract key details from each study, and synthesize the studies by theme while noting agreements, contradictions and gaps. Synonyms matter because one term misses studies that used another name.
How do you evaluate whether a research article is a reliable source?
Judge a source on peer review, sample quality, measurement validity, design appropriateness, statistical rigor and transparency. Ask whether experts reviewed it, whether the sample is adequate and representative, whether the measures are reliable and valid, whether the design can support its conclusions, whether effect sizes are reported alongside p values, and whether the methods are detailed enough to replicate. Passing peer review alone does not mean a study answers your question well.
What are the main types of plagiarism in academic writing?
The four main types are direct, paraphrase, mosaic and self-plagiarism. Direct plagiarism copies text word for word without quotation marks or citation. Paraphrase plagiarism restates a source's ideas in different words without citing it. Mosaic plagiarism mixes a source's phrases into your own writing without attribution. Self-plagiarism reuses your own previously submitted work without disclosure. Careful notes and citing even paraphrased ideas prevent most cases.

About the Research Methods in Psychology course

How many college credits is Research Methods in Psychology?
Research Methods in Psychology (Psychology 111) carries a NCCRS credit recommendation for 3 semester credits. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
How much does Research Methods in Psychology cost and what is included?
$250, paid once, with lifetime access: all 94 video lessons, a practice quiz after each, the graded work and final exam, and an official transcript when you finish. Students who want several courses choose UPI Study PRO instead.
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It is self-paced with no deadlines. The 94 lessons total about 16 hours of video; most students add reading and practice time and finish in a few weeks to a few months, on their own schedule.
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