# How to Create a Literature Review Matrix in Excel ## Quick Answer - Use a literature review matrix in Excel to track sources, key findings, and quality assessments in one sortable table. - Build columns for citation details, study design, population, outcomes, and quality notes, then apply filters to compare evidence across studies. - A matrix organizes sources but does not replace critical appraisal or reporting guidelines required for systematic reviews. ## What a Literature Review Matrix Does A literature review matrix is a structured table that helps researchers organize, compare, and synthesize information from multiple sources. For biology studies and other life science fields, the matrix serves as a central repository where each row represents one source and each column captures a specific attribute of that source. This structure allows researchers to sort, filter, and review their evidence base systematically. The matrix approach addresses a common problem in research: managing dozens or hundreds of sources while maintaining a clear view of what each study contributes. Without a structured tool, researchers often lose track of methodological details, sample sizes, and key findings across papers. The Excel format provides a practical solution because it is widely available, supports sorting and filtering, and allows customization for specific research questions. Researchers can use the matrix throughout the entire literature review process. During the search phase, the matrix tracks which databases were searched and which search terms were used. During screening, it records decisions about inclusion and exclusion. During synthesis, it enables comparisons across studies by displaying key characteristics side by side. ## Core Principles for Building a Matrix ### Define Your Research Question First Before creating columns in Excel, clarify the research question that the literature review will answer. The question determines which source attributes matter most. For a biology literature review, relevant attributes might include species studied, experimental conditions, sample size, measurement methods, and statistical approaches. A well defined question also guides the search strategy and helps establish inclusion and exclusion criteria. ### Select Reporting Guidelines Early Reporting guidelines provide checklists for transparent research reporting and help researchers know what information to extract from each study. The [EQUATOR Network](https://www.equator-network.org/) maintains a comprehensive collection of reporting guidelines for different study types. Selecting the appropriate guideline before building the matrix ensures that the columns capture the information needed for complete and transparent reporting. For example, a systematic review of animal studies would use different reporting expectations than a narrative review of ecological field observations. The EQUATOR Network resource helps identify which guideline applies to the planned review type. ### Plan for Data Management The [NIH Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy) describes expectations for managing and sharing research data. While this policy applies to NIH funded research, the underlying principles of organized data management apply broadly. A literature review matrix is a form of research data, and planning how it will be organized, stored, and potentially shared should happen early in the project. Consider how the matrix will be documented so that another researcher could understand the extraction process. Column definitions, inclusion criteria, and screening decisions should be recorded either within the matrix itself or in a companion document. ## Setting Up the Excel Template ### Essential Columns for Biology Literature Reviews The exact columns depend on the research question, but most biology literature review matrices benefit from these categories: | Column Category | Example Columns | Purpose | |-----------------|-----------------|---------| | Citation Information | Authors, Year, Title, Journal, DOI | Identify and retrieve the source | | Study Design | Study type, Species, Sample size, Duration | Assess methodology and comparability | | Intervention or Exposure | Treatment groups, Doses, Conditions | Capture experimental details | | Outcomes | Primary outcomes, Secondary outcomes, Effect sizes | Record what the study measured | | Quality Assessment | Risk of bias, Limitations, Funding source | Evaluate evidence strength | | Extraction Notes | Key findings, Relevance to review question, Quotes | Support synthesis and writing | ### Formatting for Sorting and Filtering Excel sorting and filtering work best when each column contains consistent data types. Use separate columns for authors and year instead of combining them into one cell. Use numeric columns for sample sizes and effect sizes so that sorting produces meaningful order. Use controlled vocabulary for categorical columns such as study design or species to avoid inconsistent entries that break filtering. Apply Excel table formatting by selecting the data range and using the Insert Table command. This creates a structured table with built in filter arrows on each column header. The table format also makes it easier to add rows without breaking formulas or formatting. ### Using Formulas for Automation Simple formulas can reduce manual work in the matrix. The COUNTIF function can tally how many studies used a particular method or species. The AVERAGE function can summarize sample sizes across studies. Conditional formatting can highlight studies with high risk of bias or flag missing data. Formulas should be tested on a small sample of rows before applying them to the full matrix. A formula error in a large matrix can be difficult to trace, so verify calculations as the matrix grows. ## Practical Workflow for Creating the Matrix ### Step 1: Draft Column Headers Start with a draft list of columns based on the research question and the relevant reporting guideline. Review the [EQUATOR Network](https://www.equator-network.org/) checklist for the planned review type and add any required reporting elements as columns. This step ensures that the matrix captures the information needed for transparent reporting later. ### Step 2: Create the Excel File Open a new Excel workbook and enter the column headers in the first row. Apply table formatting to create a structured table. Name the table so that formulas can reference it clearly. Save the file with a descriptive name that includes the review topic and version date. ### Step 3: Test with Five Sources Enter data for five representative sources before processing the full set of papers. This test reveals problems with column definitions, ambiguous categories, or missing information. Adjust the columns based on this trial before investing time in full data extraction. ### Step 4: Extract Data Systematically Work through the included studies one at a time, entering data for each column. Record extraction decisions consistently. If a study does not report a particular attribute, enter "NR" for not reported instead of leaving the cell blank. This distinction matters during synthesis because it separates missing information from information that was not applicable. ### Step 5: Verify and Clean the Data After entering all sources, review the matrix for errors. Sort each column alphabetically to spot inconsistent entries. Use filters to check that categorical columns contain only the approved terms. Verify that numeric columns contain numbers and not text that will break calculations. ### Step 6: Use Filters for Synthesis Apply filters to explore patterns across the evidence. Filter by study design to compare results from different methodologies. Filter by species to see which organisms have been studied. Filter by quality assessment to focus synthesis on the strongest evidence. ## Records and Measurements to Track ### Search Documentation Record the databases searched, the search date, and the search strategy used. This documentation supports reproducibility and is often required when reporting a systematic review. The matrix can include a column for search source or a separate search log can be maintained alongside the matrix. ### Screening Decisions Track which sources were excluded and why. Common exclusion reasons include wrong population, wrong outcome, insufficient data, or duplicate publication. Recording these decisions in the matrix or a companion log demonstrates that the review process was systematic and transparent. ### Quality Assessment Scores If the review includes formal quality assessment, record the scores or ratings in the matrix. The assessment tool should be selected based on the study designs included in the review. The [EQUATOR Network](https://www.equator-network.org/) provides guidance on selecting appropriate tools for different study types. ### Data Extraction Timestamps Record when each source was extracted and by whom. This information supports accountability and helps resolve discrepancies if multiple reviewers extract data from the same sources. ## Common Failure Patterns and How to Avoid Them ### Inconsistent Column Entries When different reviewers enter different terms for the same concept, filtering and sorting become unreliable. Prevent this by creating a data dictionary that defines each column and lists acceptable entries. Use Excel data validation to restrict entries to the approved list where possible. ### Overly Broad Columns Columns that try to capture too much information become difficult to use. For example, a single "Findings" column that mixes statistical results, author interpretations, and reviewer notes makes synthesis harder. Split broad columns into specific ones such as "Primary outcome measure," "Effect size," and "Author conclusion." ### Missing Source Identifiers A matrix without DOIs or full citations creates retrieval problems during writing. Always include a unique identifier for each source. The DOI is preferred because it is stable and links directly to the published article. ### Formula Errors Formulas that reference the wrong range or use incompatible data types produce errors that undermine trust in the matrix. Test formulas on small datasets and review calculated values against manual counts periodically. ### Version Confusion Multiple versions of the matrix can create uncertainty about which file is current. Use a clear file naming convention that includes the date and version number. Store the current version in a consistent location and archive older versions separately. ## Quality Controls and Verification ### Double Extraction for Critical Studies For systematic reviews, having two reviewers independently extract data from each study and then compare results reduces errors. Discrepancies are resolved through discussion or a third reviewer. This process is resource intensive, so it is often reserved for the most important outcomes or the highest risk studies. ### Regular Data Audits Periodically audit a random sample of matrix entries against the original sources. This check verifies that data were transcribed accurately and that no columns were skipped. The audit results should be recorded so that any systematic problems can be corrected. ### Peer Review of the Matrix Ask a colleague to review the matrix structure and a sample of entries. A fresh perspective can identify ambiguous column definitions or missing attributes that the primary reviewer overlooked. ## Limitations of the Matrix Approach ### Not a Substitute for Critical Appraisal The matrix organizes information but does not evaluate the quality of individual studies. Researchers must still assess risk of bias, methodological rigor, and relevance to the research question. The matrix can display quality ratings, but the ratings themselves require careful judgment. ### Limited Capacity for Complex Data Excel matrices work well for structured, categorical data but struggle with complex qualitative findings or detailed statistical results. For reviews that require extensive narrative synthesis, a matrix may need to be supplemented with full text extraction documents or qualitative analysis software. ### Risk of Oversimplification Reducing a study to a single row in a matrix can obscure important nuances. Study context, methodological details, and limitations may not fit neatly into predefined columns. Researchers should maintain access to full text sources and record important caveats in the extraction notes column. ### Maintenance Burden Large literature reviews can involve hundreds of sources, and maintaining a matrix for all of them requires consistent effort. Researchers should allocate time for data entry, verification, and updates as new sources are identified. ## Safety and Regulatory Context ### Research Integrity and Publication Ethics The [Committee on Publication Ethics Core Practices](https://publicationethics.org/core-practices) describe expectations for authorship, data handling, and misconduct reporting. A literature review matrix supports research integrity by documenting the evidence base and the decisions made during the review process. Transparent documentation helps prevent selective reporting and supports accountability. ### Data Management Expectations The [NIH Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy) outlines expectations for managing and sharing research data. While the policy applies to NIH funded research, the principles of organized data management apply broadly. A literature review matrix should be stored securely, backed up regularly, and documented so that it can be understood by others. ### Researcher Identity and Attribution The [ORCID for Researchers](https://info.orcid.org/researchers) resource describes how researchers can maintain a persistent digital identifier that links their work across publications and affiliations. Using ORCID in the citation information within the matrix helps ensure accurate attribution and simplifies author identification during the writing process. ### Funding and Grant Context The [NIH Grants and Funding](https://grants.nih.gov/) portal provides official information about grant policy, application, and award management. For researchers planning a literature review as part of a grant application, the matrix can serve as preliminary evidence of the research landscape and support the justification for the proposed study. ## Professional Escalation Criteria ### When to Seek Methodological Guidance If the literature review will be published as a systematic review, consult a librarian or methodologist with systematic review expertise before finalizing the matrix structure. The [EQUATOR Network](https://www.equator-network.org/) can help identify the appropriate reporting guideline, but methodological support may be needed for complex reviews. ### When to Consult Institutional Resources If the research involves human subjects, animal subjects, or sensitive data, consult the relevant institutional review board or ethics committee before beginning the review. The [Committee on Publication Ethics Core Practices](https://publicationethics.org/core-practices) provide context on ethical expectations, but institutional requirements may be more specific. ### When to Escalate Data Management Concerns If the matrix contains sensitive or proprietary data, consult institutional data management staff about secure storage and sharing requirements. The [NIH Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy) provides a framework for planning, but institutional policies may impose additional requirements. ## Decision Framework for Source Prioritization and Synthesis ### Why a Prioritization Framework Matters A literature review matrix that treats every source equally creates a hidden problem during synthesis. When researchers have dozens of studies with varying relevance and quality, the writing phase becomes difficult because the matrix does not indicate which sources should carry more weight in the final narrative. A structured decision framework built into the matrix helps researchers move from organization to synthesis with clear, defensible choices about which studies anchor the review and which provide supporting context. The framework operates on a simple principle: not all sources contribute equally to answering the research question. Some studies directly test the central hypothesis, others provide background context, and some may be included but carry significant methodological limitations. Without a way to distinguish these roles, the matrix becomes a flat list instead of a decision tool. ### Building a Three Tier Priority System Create a column labeled "Priority Tier" in the matrix and assign each source one of three values: Tier 1, Tier 2, or Tier 3. This classification should be applied after data extraction and quality assessment, not during initial screening, because the priority depends on both relevance and methodological strength. Tier 1 sources directly address the primary research question, use appropriate study designs, and pass basic quality checks. These studies form the backbone of the synthesis and should be described in the most detail in the final review. For a biology literature review, a Tier 1 study might be a controlled experiment with adequate sample size that measures the exact outcome of interest in the target species. Tier 2 sources provide valuable supporting evidence but have limitations that prevent them from anchoring the synthesis. These might include studies with smaller sample sizes, indirect outcome measures, or methodological constraints that reduce confidence in the findings. Tier 2 sources can corroborate Tier 1 findings, provide context, or fill gaps where Tier 1 evidence is sparse. Tier 3 sources offer background information, methodological descriptions, or preliminary findings that do not directly answer the research question. These sources support the introduction and discussion sections but should not drive the synthesis conclusions. Review articles, opinion pieces, and studies with major methodological flaws typically fall into this tier. ### Applying the Framework with Excel Tools Use conditional formatting to color code the Priority Tier column so that Tier 1, Tier 2, and Tier 3 entries are visually distinct. This allows quick visual scanning of the matrix to see the distribution of evidence quality across the review. Use the filter function to isolate Tier 1 sources when drafting the results synthesis. This focused view helps the researcher see the strongest evidence without distraction from supporting sources. Similarly, filter to Tier 3 sources when writing background sections to identify which studies provide context instead of direct evidence. The COUNTIF function can tally how many sources fall into each tier. This count provides a quick snapshot of the evidence base and can reveal imbalances, such as a review that relies heavily on Tier 3 sources with few Tier 1 studies. Such a finding may indicate that the research question needs refinement or that the search strategy missed key studies. ### Recording Priority Decisions The priority tier assignment should be recorded with a brief justification in a companion column labeled "Priority Rationale." This column captures why a source received its tier, such as "directly tests primary outcome in target species" or "small sample size limits confidence." This documentation serves two purposes. First, it forces the researcher to articulate the reasoning behind each classification, which reduces arbitrary assignments. Second, it provides a transparent record that can be reviewed by collaborators or mentioned in the methods section of the final paper. The [Committee on Publication Ethics Core Practices](https://publicationethics.org/core-practices) emphasize transparency in research conduct. Documenting priority decisions supports this expectation by showing that source weighting was based on explicit criteria instead of implicit preference. ### Revisiting Tier Assignments During Synthesis Priority tiers should not be treated as permanent once assigned. As the researcher reads sources in depth during the synthesis phase, new information may emerge that changes the assessment of a study. A source initially classified as Tier 2 might be elevated to Tier 1 if closer reading reveals that its methodology is stronger than the initial screening suggested. Conversely, a Tier 1 source might be downgraded if the full text reveals undisclosed limitations. Schedule a review of tier assignments after the first full read of all included sources and again after the first draft of the synthesis. This iterative approach ensures that the priority framework reflects the deepest understanding of the evidence instead of first impressions. ### Handling Disagreements Between Reviewers When multiple reviewers work on the same literature review, disagreements about priority tiers will occur. Establish a simple resolution process before disagreements arise. Each reviewer assigns tiers independently, then the team compares assignments and discusses discrepancies. The discussion should focus on the explicit criteria for each tier instead of personal preferences about individual studies. If the team cannot reach consensus on a particular source, the default should be to assign the higher tier only when both reviewers agree that the source meets the criteria. When in doubt, assign the lower tier and document the disagreement in the Priority Rationale column. This conservative approach prevents over weighting sources with contested quality. ### Using the Framework for Gap Analysis The priority framework also supports gap analysis, which identifies areas where the evidence base is thin. Filter the matrix by Tier 1 sources and examine which subtopics within the research question have few or no Tier 1 studies. These gaps become important points in the discussion section where the researcher acknowledges limitations of the current evidence and suggests directions for future research. For example, a biology review might find that Tier 1 evidence exists for the effects of a treatment on adult organisms but that no Tier 1 studies examine juvenile organisms. This gap becomes a clear statement about the limits of current knowledge and a justification for future work. The [NIH Grants and Funding](https://grants.nih.gov/) portal describes how grant applications often require identification of knowledge gaps, and the matrix with priority tiers provides documented evidence of where those gaps exist. ### Integrating the Framework with Reporting Guidelines The priority framework complements instead of replaces reporting guidelines. The [EQUATOR Network](https://www.equator-network.org/) provides checklists that specify what information should be reported in the final review. The priority framework helps the researcher decide how much weight each source receives in the narrative, while the reporting guideline ensures that the review process is described transparently. When writing the methods section, describe the priority framework explicitly. State the criteria for each tier and explain how tier assignments were made and verified. This description allows readers to understand how the synthesis weighted different sources and provides transparency about the decision process. ### Common Mistakes in Priority Assignment One common mistake is assigning priority based on the prominence of the journal or the authors instead of the study characteristics. A study from a high profile journal with a weak design should not automatically receive Tier 1 status. The framework should evaluate the study itself, not its publication venue. Another mistake is treating tier assignment as a quality score. Tier 1 does not mean the study is flawless, and Tier 3 does not mean the study is worthless. The tier reflects the source's role in answering the specific research question, which combines relevance with methodological strength. A well conducted study on a tangential topic may be Tier 3 because it does not directly address the review question, not because it is poorly done. A third mistake is failing to update tiers as the review progresses. The framework works best when it is treated as a living tool that reflects the researcher's evolving understanding of the evidence. Stale tier assignments from the initial screening phase may not reflect the deeper insights gained during full text reading and synthesis. ### Practical Implementation Steps To implement the priority framework in an existing matrix, add two columns: "Priority Tier" and "Priority Rationale." Apply conditional formatting to the Priority Tier column using green for Tier 1, yellow for Tier 2, and red for Tier 3. Enter tier assignments for all sources after completing quality assessment. Write a one sentence rationale for each assignment in the companion column. After the first draft of the synthesis is complete, review all tier assignments again. Check whether the sources that anchor the synthesis are all Tier 1 and whether any Tier 2 or Tier 3 sources are carrying more weight than their classification suggests. Adjust assignments as needed and update the rationale column to reflect the revised thinking. The framework should be described in the methods section of the final review. State the criteria for each tier, the process for assigning tiers, and how disagreements were resolved. This description supports the transparency expectations described in the [Committee on Publication Ethics Core Practices](https://publicationethics.org/core-practices) and helps readers understand how the synthesis was constructed. ## Frequently Asked Questions ### What is the difference between a literature review matrix and a summary table? A literature review matrix is a working tool used during the review process to organize and compare sources. A summary table is a polished product that appears in the final manuscript to present key characteristics of included studies. The matrix often contains more columns and more detailed notes than the final summary table. ### How many columns should a literature review matrix have? The number of columns depends on the research question and the reporting requirements for the review type. A simple matrix might have 8 to 10 columns, while a complex systematic review matrix could have 20 or more. Start with the minimum columns needed to answer the research question and add columns only when they serve a clear purpose. ### Can I use Google Sheets instead of Excel for a literature review matrix? Google Sheets supports sorting, filtering, and formulas similar to Excel and offers the advantage of real time collaboration. The choice depends on team preferences and institutional software availability. The principles for building the matrix are the same regardless of the spreadsheet application. ### How do I handle studies that do not report certain information? Enter "NR" for not reported in the relevant cell instead of leaving it blank. This distinction matters during synthesis because it separates missing information from information that was not applicable. During the writing phase, the frequency of "NR" entries can highlight reporting gaps in the literature. ### Should I include quality assessment scores in the matrix? Yes, if the review includes formal quality assessment. Record the assessment tool used and the score or rating for each study. This information supports transparent reporting and allows readers to understand how quality was evaluated. ### How do I keep the matrix updated as I find new sources? Add new sources as rows in the table format so that formulas and formatting extend automatically. Run the same verification checks on new entries that were applied to the original data. Update the search documentation to reflect the date when new sources were identified. ### Can the matrix be used for a narrative review or only a systematic review? The matrix works for both narrative and systematic reviews. For a narrative review, the matrix helps organize sources and identify themes across the literature. For a systematic review, the matrix supports the structured extraction and synthesis required by reporting guidelines. ### How do I cite the sources in my matrix when writing the final paper? Use the citation information recorded in the matrix to generate the reference list according to the target journal or style guide. The DOI recorded in the matrix provides a stable link for verification. The [ORCID for Researchers](https://info.orcid.org/researchers) resource can help confirm author identities when multiple authors share similar names. ## Using the Evidence | Source | Best use in this topic | Important limitation | |---|---|---| | [Research Methods Resources](https://www.ncbi.nlm.nih.gov/books) | official guidance | Check the linked page for current local requirements | | [EQUATOR Network](https://www.equator-network.org/) | official guidance | Check the linked page for current local requirements | | [Core Practices](https://publicationethics.org/core-practices) | official guidance | Check the linked page for current local requirements | ## Related Articles - [Data Management Plan Template: A Practical Guide for Researchers](/blog/guides/data-management-plan-template-a-practical-guide-for-researchers) - [Scientific Literature Review Format: A Reproducible Structure for Researchers](/blog/careers/scientific-literature-review-format-a-reproducible-structure-for-researchers) - [The Role of the Research Ethics Committee: What Researchers Need to Know](/blog/guides/the-role-of-the-research-ethics-committee-what-researchers-need-to-know) - [biology research jobs](/blog/news/biology-research-jobs) - [Protein Synthesis Step By Step](/blog/guides/protein-synthesis-step-by-step) ## References and Further Reading - [Research Methods Resources](https://www.ncbi.nlm.nih.gov/books). National Library of Medicine. - [EQUATOR Network](https://www.equator-network.org/). EQUATOR Network. - [Core Practices](https://publicationethics.org/core-practices). Committee on Publication Ethics. - [NIH Grants and Funding](https://grants.nih.gov/). National Institutes of Health. - [ORCID for Researchers](https://info.orcid.org/researchers). ORCID. - [Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy). National Institutes of Health. - [NCBI Literature Resources](https://www.ncbi.nlm.nih.gov/). National Center for Biotechnology Information. - [PubMed](https://pubmed.ncbi.nlm.nih.gov/). National Library of Medicine. > This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.