# Impact Factor vs. CiteScore vs. Eigenfactor

## Quick Answer

- Choose a journal metric based on your specific decision: CiteScore for broad interdisciplinary visibility, Eigenfactor for influence within core literature, and Impact Factor for traditional prestige comparisons.
- Match the metric to your field's citation culture, since life-science disciplines vary widely in how quickly and how often papers get cited.
- No single metric predicts a journal's true quality, so use multiple measures alongside editorial standards and ethics policies.

## Understanding Journal Metrics in Life Sciences

Journal metrics serve as quantitative tools that researchers, hiring committees, and funding agencies use to evaluate where scientific work appears. These numbers attempt to measure scholarly influence, but each one calculates influence differently. The three most commonly discussed metrics are the Journal Impact Factor, CiteScore, and Eigenfactor. Each answers a different question about a journal's role in the scientific literature.

The Journal Impact Factor has been used since the 1960s and remains the most recognized metric in academic publishing. CiteScore emerged in 2016 as an alternative from a different indexing database. Eigenfactor takes a fundamentally different approach by modeling how citations flow through the entire network of journals. Understanding these differences matters for practical decisions about where to submit research, how to evaluate journals for collaboration, and how to interpret metrics when reviewing candidates or programs.

For animal and life-science professionals, the choice of journal affects career advancement, grant applications, and the reach of research findings. A paper published in a journal with high visibility in the right community can influence practice guidelines, policy discussions, and future research directions. The metric that matters most depends on whether you need broad readership, influence among specialists, or recognition from traditional academic structures.

## At a Glance

| Metric | What It Measures | Calculation Basis | Best Used For | Key Limitation |
|--------|------------------|-------------------|---------------|----------------|
| Impact Factor | Average citations per citable item in a specific year | Citations in year X to items published in years X-1 and X-2, divided by citable items in those years | Comparing established journals in similar fields | Two-year window misses slower-citing disciplines and review-heavy journals |
| CiteScore | Average citations per document over four years | Citations in year X to items published in years X-4 through X-1, divided by all document types | Comparing journals across broader timeframes and newer journals | Includes all document types, which can inflate values for journals with many editorials |
| Eigenfactor | Influence of a journal within the citation network | Citation-weighted PageRank-style algorithm over five years | Identifying journals that shape core literature in a field | Less intuitive to interpret and not widely understood by non-specialists |

## How the Impact Factor Works

The Journal Impact Factor calculates the average number of citations received in a given year by articles published in the two preceding years. For example, the 2024 Impact Factor for a journal would count citations received during 2024 to articles published in 2022 and 2023, then divide that number by the total count of citable items published in those same two years.

This metric rewards journals that attract citations quickly after publication. Research areas with rapid citation cycles, such as molecular biology and genetics, tend to produce higher Impact Factors than fields where knowledge accumulates slowly. Review articles typically receive more citations than original research, so journals publishing many reviews often show elevated Impact Factors.

The two-year window creates specific practical consequences. A journal in a field where researchers take several years to read, digest, and cite new work will appear less influential than a journal in a fast-moving field, even if its long-term influence is substantial. Animal science and veterinary medicine often operate on slower citation cycles because research findings must move through applied testing and field validation before they get cited in subsequent work.

For researchers deciding where to submit, the Impact Factor provides a familiar benchmark that search committees and promotion panels recognize. However, the metric says nothing about the quality of individual articles. A journal with a high Impact Factor can publish papers that receive few or no citations, just as a journal with a modest Impact Factor can publish landmark work.

## How CiteScore Works

CiteScore uses a four-year citation window, which captures a longer period of scholarly influence than the Impact Factor. The calculation divides citations received in a given year by documents published in the previous four years. This broader window accommodates fields where research takes longer to gain traction.

CiteScore also counts all document types in its denominator, including editorials, letters, and news items, whereas the Impact Factor counts only citable items such as research articles and reviews. This difference means CiteScore can appear lower for journals that publish many non-research items, even when those items attract citations.

The four-year window makes CiteScore useful for comparing journals in applied fields where research findings move into practice gradually. Veterinary clinical research, animal nutrition studies, and livestock management research often follow this pattern. A paper describing a new feeding protocol might not get cited until other research groups replicate the findings or extension services incorporate the results into recommendations.

CiteScore values come from the Scopus database, which indexes a broader range of journals than the database used for Impact Factor calculations. This broader coverage means CiteScore can provide information about journals that do not have Impact Factors, including newer journals and those from regional publishers. For researchers exploring submission options beyond the most established titles, CiteScore offers a way to compare journals that might otherwise lack quantitative evaluation.

## How Eigenfactor Works

Eigenfactor takes a network-based approach to measuring journal influence. Instead of simply counting citations, the algorithm models how citations flow through the entire journal network, similar to how search engines rank web pages based on links from other important pages. A citation from a highly influential journal carries more weight than a citation from a peripheral journal.

The Eigenfactor score reflects the total influence of a journal across the scholarly network over a five-year period. This approach captures the idea that being cited by important work matters more than being cited by obscure work. A journal that publishes foundational methods papers might receive fewer total citations than a flashy journal, but those citations could come from influential research groups and appear in high-status publications.

Eigenfactor also accounts for the structure of citation networks. Journals in densely connected fields where researchers cite each other frequently will show different patterns than journals in fragmented fields. The metric normalizes for differences in field size, making it possible to compare journals across disciplines in ways that raw citation counts cannot.

For animal and life-science researchers, Eigenfactor provides insight into which journals actually shape the direction of research. A journal that publishes systematic reviews and meta-analyses might have a high Eigenfactor because those papers get cited across many subfields. Similarly, a journal that publishes methodological innovations can accumulate influence as other researchers adopt and adapt those methods.

## Comparing the Three Metrics

The three metrics answer different questions about journal performance. The Impact Factor asks how quickly a journal's recent articles get cited. CiteScore asks how consistently a journal's articles get cited over a moderate timeframe. Eigenfactor asks how much a journal shapes the broader conversation in its field.

For practical decision-making, researchers should consider which question matters most for their specific situation. A graduate student seeking a first publication might prioritize a journal with a strong Impact Factor because that number carries weight in academic job markets. A researcher in an applied field might prefer a journal with a strong CiteScore because the four-year window better reflects how work in that field gets used. A senior researcher developing a research program might look at Eigenfactor to identify journals that will position their work within the most influential scholarly networks.

The metrics also differ in their susceptibility to gaming. Impact Factor can be influenced by editorial practices such as publishing many review articles or encouraging authors to cite the journal. CiteScore's inclusion of all document types creates different incentives. Eigenfactor's network approach makes it harder to manipulate because it depends on citation patterns across the entire scholarly ecosystem.

None of these metrics directly measures the quality of peer review, the rigor of editorial standards, or the ethical practices of a journal. A journal can have strong metrics while failing to follow basic publication ethics. Researchers should evaluate journals using multiple sources of information, including the [Core Practices](https://publicationethics.org/core-practices) established by the Committee on Publication Ethics, which cover authorship, peer review, data handling, conflicts of interest, and misconduct procedures.

## Choosing a Metric for Your Decision

### For Journal Submission Decisions

When deciding where to submit a manuscript, consider the citation patterns of your specific research area. Look at where papers you cite most frequently appear and where related work in your field gets published. The metric that matters is the one used by the people who will evaluate your career, whether that is a hiring committee, a promotion panel, or a funding agency.

For animal science research, the choice often depends on whether your work targets basic mechanisms or applied outcomes. Basic research on animal physiology or genetics might fit journals with high Impact Factors because that work competes in fast-moving fields. Applied research on livestock management or veterinary practice might find better homes in journals with strong CiteScores because practitioners and extension specialists read those journals and cite them over longer periods.

### For Evaluating Journals

When evaluating a journal for collaboration, reading, or recommending to students, look beyond any single metric. Examine the journal's editorial board, its peer review process, and its policies on data sharing and ethical oversight. The [Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy) from the National Institutes of Health reflects the growing expectation that research data be accessible and well-documented, and journals increasingly require authors to follow such standards.

Check whether the journal follows recognized reporting guidelines. The [EQUATOR Network](https://www.equator-network.org/) maintains a comprehensive collection of reporting guidelines for different study types, and journals that require authors to follow these guidelines tend to publish more transparent and reproducible research.

### For Career and Funding Decisions

Researchers preparing for promotion or grant applications should understand which metrics their institution or funding agency uses. The [NIH Grants and Funding](https://grants.nih.gov/) pages describe how applications are reviewed, and while they do not specify journal metrics, the review process emphasizes the significance and impact of proposed research. A strong publication record in journals that reach the right audience matters more than any single number.

Maintaining an accurate [ORCID record](https://info.orcid.org/researchers) ensures that your publications are correctly attributed to you. This becomes important when evaluators use automated tools to assess publication records, since misattributed or missing publications can distort the picture of your scholarly output.

## Practical Assessment Steps

### Step 1: Define Your Purpose

Write down the specific decision you need to make. Are you choosing a journal for a manuscript, evaluating a journal for a collaboration, or preparing materials for a promotion case? Each purpose calls for different metrics and different supplementary information.

### Step 2: Gather Metric Data

Look up the Impact Factor, CiteScore, and Eigenfactor for the journals you are considering. Record the values in a spreadsheet along with the year of each metric. Metrics change annually, so note which year you are using for each comparison.

### Step 3: Examine Field-Specific Patterns

Identify the citation patterns in your research area. Look at the reference lists of recent papers in your field and note which journals appear most frequently. This observation tells you which journals your colleagues actually read and cite, regardless of what any metric says.

### Step 4: Review Journal Policies

Visit the journal's website and examine its editorial policies. Look for statements about peer review, data availability, authorship criteria, and conflict of interest handling. Compare these policies against the [Core Practices](https://publicationethics.org/core-practices) from the Committee on Publication Ethics.

### Step 5: Check Reporting Standards

Determine whether the journal requires authors to follow reporting guidelines appropriate for their study type. The [EQUATOR Network](https://www.equator-network.org/) provides a searchable database of guidelines, and journals that mandate these standards demonstrate commitment to research transparency.

### Step 6: Document Your Decision

Record your reasoning for choosing or rejecting each journal. Note which metrics you considered, what policies you reviewed, and any concerns you identified. This documentation helps when you need to explain your choices to supervisors, collaborators, or review committees.

## Records and Measurements

Maintain a journal evaluation log that tracks the metrics and policies of journals you consider. For each journal, record the Impact Factor, CiteScore, and Eigenfactor for the current year, along with the date you checked each value. Note any changes in editorial leadership, scope, or policies that might affect the journal's direction.

Track citation patterns for your own published work. After your papers appear, monitor where they get cited and how quickly. This observation helps you understand whether the journals you chose are reaching the audiences you intended. If your work in an applied field gets cited slowly but steadily, a four-year metric like CiteScore might reflect your experience better than a two-year metric.

Keep records of submission outcomes, including review times, acceptance rates, and reviewer feedback. These practical observations provide information that no journal metric captures. A journal with excellent metrics but slow, unhelpful reviews might not serve your career needs as well as a journal with slightly lower metrics and efficient, constructive peer review.

## Common Failure Patterns

### Overweighting a Single Metric

Researchers often choose journals based entirely on Impact Factor without considering whether that metric matches their field's citation patterns. This approach leads to submissions to journals that may not reach the right audience or may reject papers that would thrive elsewhere.

### Ignoring Field Differences

Comparing metrics across different disciplines produces misleading conclusions. A high Impact Factor in animal science might be modest compared to molecular biology, but that does not mean the animal science journal is less influential within its own field. Always compare journals within the same discipline.

### Confusing Journal Metrics with Article Quality

A paper published in a high-metric journal does not automatically receive many citations. Conversely, important papers can appear in journals with modest metrics. The metric describes the journal's average performance, not the fate of any individual article.

### Neglecting Ethical Standards

Journals with strong metrics can still have weak editorial oversight. Before submitting, verify that the journal follows ethical publishing practices. The [Core Practices](https://publicationethics.org/core-practices) from the Committee on Publication Ethics provide a framework for evaluating a journal's commitment to responsible publishing.

### Failing to Update Assessments

Journal metrics change annually, and editorial policies can shift with new leadership. A journal that was a good fit five years ago might have changed its scope, review standards, or publication practices. Reassess journals periodically instead of relying on past evaluations.

## Limitations of Journal Metrics

All journal metrics share fundamental limitations. They measure aggregate citation patterns, not the quality or importance of individual articles. They cannot capture the impact of research that influences practice guidelines, policy decisions, or industry standards without being formally cited. They also cannot account for the growing importance of preprints, datasets, software, and other research outputs that do not fit traditional citation counting.

Metrics also lag behind the actual state of a journal. The numbers reflect citation patterns from previous years, so a journal that has recently improved its editorial standards or changed its scope will not show those changes in its metrics for several years. Conversely, a journal that has declined in quality may continue to show strong metrics based on past performance.

For researchers in applied fields, the limitations of citation-based metrics are particularly relevant. Work that influences veterinary practice, animal management protocols, or agricultural policy may have substantial real-world impact without generating corresponding citation counts. Practitioners who read and apply research findings do not always publish papers that cite the work they use.

The [Research Methods Resources](https://www.ncbi.nlm.nih.gov/books) from the National Library of Medicine provide guidance on understanding research quality and evidence hierarchies. These resources help researchers think about the broader context of scholarly communication beyond simple citation counts.

## Welfare and Safety Context

For animal and life-science research, the choice of publication venue connects to broader responsibilities. Research involving animals must follow ethical standards for animal care and use, and the journals where such work appears should require authors to document compliance with those standards. When evaluating journals, check whether they require statements about animal welfare approvals and whether they follow the ethical principles outlined in the [Core Practices](https://publicationethics.org/core-practices) from the Committee on Publication Ethics.

Data management also carries welfare implications. Research on animal health and production often generates data that could inform future studies, improve animal care, or support policy decisions. The [Data Management and Sharing Policy](https://sharing.nih.gov/data-management-and-sharing-policy) from the National Institutes of Health reflects the expectation that research data be preserved and shared appropriately. Journals that support data sharing contribute to a research ecosystem where findings can be verified and built upon.

Researchers should also consider the safety context of their work. Studies involving animal pathogens, zoonotic diseases, or agricultural chemicals may have implications for human and animal health. Publishing in journals with rigorous peer review and transparent reporting standards helps ensure that such work is communicated accurately and responsibly.

## Professional Escalation Criteria

Seek guidance from mentors, supervisors, or institutional research offices when you encounter situations that exceed your experience. If you are uncertain about which metric matters for a specific career decision, consult someone who has served on hiring or promotion committees in your field. If you are considering a journal that seems unfamiliar or that you cannot verify through established databases, ask a librarian or research office for assistance.

Escalate concerns about journal ethics to appropriate authorities. If you suspect a journal is engaging in predatory practices, failing to conduct genuine peer review, or violating publication ethics, report your concerns to your institution's research integrity office. The [Core Practices](https://publicationethics.org/core-practices) from the Committee on Publication Ethics describe the standards that responsible journals should meet.

When preparing grant applications, consult with your institutional grants office about how to present your publication record. The [NIH Grants and Funding](https://grants.nih.gov/) pages provide official information about application requirements and review processes. Your grants office can help you understand how to frame your publication history in ways that align with reviewer expectations.

For questions about research reporting and methodology, consult the [EQUATOR Network](https://www.equator-network.org/) to identify the appropriate reporting guideline for your study type. Following these guidelines improves the quality and transparency of your research, which matters more than any journal metric.

## Frequently Asked Questions

### Which metric should I use to compare journals in animal science?

Use CiteScore as your primary comparison tool for animal science journals because the four-year window better matches the citation patterns of applied research. Supplement this with Eigenfactor to understand which journals carry the most influence in the field's core literature. Check the Impact Factor only when comparing against journals in other disciplines or when your institution specifically requires it.

### Why does my field have lower Impact Factors than molecular biology?

Fields with slower citation cycles naturally produce lower Impact Factors because the two-year window does not capture citations that accumulate over longer periods. Applied research in animal science often takes years to influence subsequent work, so the four-year window used by CiteScore provides a more accurate picture of influence in these fields.

### Can a journal have a high Impact Factor but poor editorial standards?

Yes. Journal metrics measure citation patterns, not editorial quality. A journal can achieve strong metrics while failing to conduct rigorous peer review or follow ethical publishing practices. Always evaluate a journal's policies against the [Core Practices](https://publicationethics.org/core-practices) from the Committee on Publication Ethics before submitting your work.

### How often do journal metrics change?

Journal metrics are recalculated annually. Impact Factor and CiteScore values are updated each year based on the previous year's citation data. Eigenfactor scores also update annually. Because metrics change, always record the year of any metric you use for comparison and check for updates before making important decisions.

### Should I avoid journals without an Impact Factor?

Not necessarily. Many legitimate journals, particularly newer ones and those from regional publishers, do not have Impact Factors but still provide rigorous peer review and reach important audiences. CiteScore covers a broader range of journals and can help you evaluate options that lack Impact Factors. Focus on editorial quality and audience fit instead of requiring a specific metric.

### How do I explain journal metrics in a job application?

Describe your publication record in terms of the journals' relevance to your field and the audiences they reach. If you mention metrics, provide context about what they mean instead of listing numbers without explanation. Committees want to understand the significance of your work, beyond the numbers attached to the journals where it appeared.

### What role do reporting guidelines play in journal selection?

Journals that require authors to follow reporting guidelines demonstrate commitment to research transparency and reproducibility. The [EQUATOR Network](https://www.equator-network.org/) provides a searchable database of guidelines for different study types. Choosing journals that mandate these standards supports the quality and credibility of your research.

### How should I track my publications for career purposes?

Maintain an up-to-date [ORCID record](https://info.orcid.org/researchers) that accurately links all your publications to your researcher profile. This ensures that your work is correctly attributed across databases and available to evaluators. Keep your record current as you publish and update it whenever your affiliation or name changes.

## 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

- [Sample Size Symbol and Notation: What You Need to Know](/blog/guides/sample-size-symbol-and-notation-what-you-need-to-know)
- [Cosmetics Regulatory Affairs Jobs: What You Need to Know](/blog/careers/cosmetics-regulatory-affairs-jobs-what-you-need-to-know)
- [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)
- [Bioinformatics vs. Computational Biology: What's the Difference (and Which Should You Choose)?](/blog/careers/bioinformatics-vs-computational-biology)
- [Bioinformatics Careers: What You Need to Know Before You Start](/blog/careers/bioinformatics-careers-what-you-need-to-know-before-you-start)

## 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.