Claim under review
“Including a cover letter increases your chance of getting an interview.”
Short answer
One genuine field experiment supports a version of this. ResumeGo submitted 7,287 fictitious applications to real job postings between July 2019 and January 2020 and found that applications with a cover letter tailored to the specific job received a 53% higher callback rate than applications with none. Two cautions matter: the study was run by a resume-writing company, and it published a relative increase without the underlying callback rates, so the result cannot be converted into an absolute change in anyone's chances.
Evidence status
A real source underlies the claim, but the claim as circulated overstates it — by generalising a narrow population, dropping a qualifier, rounding a range to a single number, or restating a measure as something it did not measure.
What we found
The experiment has a genuine randomised design with three arms — no cover letter, a generic one, and one tailored to the posting — which is rare in this literature.
The reported effect is relative. Without the callback rate for each group, a 53% increase could describe a move from a small rate to a slightly less small one, and the difference in practical terms is unknowable from what is published.
The applications were fictitious. This is standard and necessary for an experiment of this kind, but it means the cover letters were written to a consistent professional standard that a real applicant's may not match.
The published summary states no limitations of its own, which is itself worth noting for a study whose publisher sells the service it evaluates.
Earliest appearance we could trace
ResumeGo's own published research summary, following fieldwork that ended 10 January 2020.
What was actually measured
- What was measured
- Callback rate by cover-letter condition across fictitious applications to real job postings.
- Population
- Job postings on general US job boards
- Sample
- 7,287 applications
- Time period
- 15 July 2019 to 10 January 2020
- Numerator
- Applications receiving a callback
- Denominator
- Applications submitted
- Unit of analysis
- Application
What the evidence supports
- That including a tailored cover letter is associated with more callbacks than including none, in this experiment.
- That tailoring matters more than merely attaching something: the generic arm performed worse than the tailored one.
What it does not support
- Any absolute statement about how much a cover letter changes an individual's chances, because no base rates were published.
- That the effect holds outside general job boards, or for senior, technical or internal hiring.
- That a cover letter written under time pressure by an applicant performs like one written for a controlled experiment.
Limitations
- Run and published by a company selling resume and cover-letter services.
- Relative effect only; no per-group callback rates, and no uncertainty interval.
- Fieldwork predates widespread generative-AI drafting, which may have changed how cover letters are read.
Jobsearch.ing interpretation
Our reading, marked as ours. Take the evidence above and reject this if you read it differently.
We think the honest summary is that the evidence points one way but cannot tell you how far. Writing a tailored letter appears to help; how much it helps for any particular application is not something this study can answer.
The absence of base rates is the kind of omission that matters. It is the difference between advice worth an hour and advice worth ten minutes, and the published study does not let a reader work out which.
Sources
The evidence packets behind this article. Each was read directly, at the table or section named in its details.
ResumeGo
Industry report · Tier 2 · Sample
7,287 fictitious applications to real US job postings, July 2019 to January 2020.
Cover Letters: Just How Important Are They?Supports
A tailored cover letter was associated with a 53% higher callback rate in a 7,287-application field experiment.
Does not
A relative increase with no base rates published cannot be turned into absolute odds.
Evidence details
- Supports (full)
- In a field experiment submitting 7,287 fictitious applications to real job postings between 15 July 2019 and 10 January 2020, applications including a cover letter tailored to the specific job received a 53% higher callback rate than applications with no cover letter.
- Does not support (full)
- The published summary reports a relative difference without the underlying callback rates for each group, so the finding cannot be converted into an absolute change in a candidate's chances. It also cannot speak to whether a real candidate's own cover letter would perform like the study's professionally written ones.
- Measure
- Rate
- Counts
- Applications receiving a callback divided by Applications submitted
- Unit
- Application
- Population
- Job postings on general job boards including ZipRecruiter, Glassdoor and Indeed, applied to with fictitious candidate profiles
- Geography
- United States
- Period
- 15 July 2019 to 10 January 2020
- Sample
- 7,287 observations
- Method
- Three-arm field experiment. Applications were assigned no cover letter, a generic cover letter, or a cover letter tailored to the posting, and callbacks were recorded.
- Found at
- Headline finding of the published research summary
- Quoted
- “applications that included cover letters tailored specifically to the job at hand had a 53% higher callback rate than applications with no cover letter”
- Notes
- Conducted and published by a resume-writing company. The design is a genuine randomised field experiment, which is unusual in this literature and worth more than the publisher's commercial interest costs it — but the absent base rates are a real limitation, and the summary states no limitations of its own.
- Record
- Published Feb 1, 2020 · Accessed Aug 22, 2026
Cite this
If you are citing the underlying figure, cite the original source — not this page. This review is a secondary analysis, and citing it in place of the primary source would repeat the mistake it documents.
Cite this review for the analysis: the source trail, the evidence status, and what the evidence does and does not support.
- First published
- Last updated
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How evidence statuses are defined, and what each one commits us to, is set out in the methodology.