Evidence standard

Case study generalizability checklist

Published June 3, 2026. Status: evergreen source page.

A case study can make a measurement problem concrete. It can also make one clean-looking result feel more repeatable than the evidence deserves.

Use this checklist when a story, vendor deck, campaign recap, renewal memo, or public example asks readers to carry a lesson from one setting into a broader decision. The question is not whether the case is useful. The question is what part of the case can travel: the mechanism, the warning sign, the observed result, the measurement design, or the causal estimate.

Generalization ladder

Start by naming the strongest claim the case can support. A detailed example is not automatically a representative pattern, and a measured result in one setting is not automatically a forecast for the next one.

Evidence level	What it can support	What it cannot support alone	Upgrade needed
Illustrative example	What a problem, decision, or measurement failure can look like.	How common, costly, typical, or causal the pattern is.	Denominator, record universe, comparable cases, or sample disclosure.
Documented case	That the described events, fields, or results occurred under the stated source trail.	That similar results should be expected elsewhere.	Case selection note, baseline, and counterexamples.
Comparable case set	A recurring pattern across similar conditions.	A precise effect size or universal rule.	Inclusion criteria, excluded cases, common denominator, and variation range.
Designed measurement case	An estimate for one audience, window, outcome, and comparison design.	Future lift in different audiences, prices, channels, creative, or timing.	Replication, sensitivity, uncertainty, and transfer limits.
Repeatable decision pattern	A practical rule for when a team should ask for a stronger comparison.	Guaranteed performance or a settled causal mechanism in every setting.	Multiple settings, stable mechanism, and clear failure conditions.

The transfer test

Before using one case to shape another decision, check which conditions are actually shared. The more the new setting differs from the case, the narrower the lesson should become.

Transfer condition	Ask first	Downgrade the claim when
Audience intent	Were people already searching, comparing, buying, returning, or reachable before the campaign?	The next audience has different pre-existing intent or eligibility.
Channel and package	Is the inventory, placement context, frequency, format, and buying path comparable?	The original result came from a different channel, package, or delivery constraint.
Creative and destination	Did message, offer, page friction, form quality, or follow-up coverage shape the result?	The new creative, landing page, or routing path changes the response opportunity.
Timing and market context	Were seasonality, promotions, pricing, news cycle, or category demand stable?	The case window had unusual timing that could explain the movement.
Outcome definition	Was the outcome a qualified visit, lead, sale, survey response, matched conversion, or modeled contribution?	The new decision cares about a different outcome or a later status window.
Comparison design	Was the baseline, holdout, matched market, or model chosen before results were visible?	The case used a weaker comparison than the new claim requires.
Uncertainty and variation	How wide was the range, how noisy were slices, and what changed under sensitivity checks?	The case is reported as a point estimate with no decision threshold or range.

Minimum case packet

A case study is easier to judge when the source trail and boundaries are visible. Ask for this packet before letting one example become a rule.

Case selection note

State why this case was chosen, what universe it came from, what similar cases were excluded, and whether it is typical, extreme, recent, convenient, or methodologically clean.

Decision and claim

Write the exact decision the case is meant to inform and the exact sentence the evidence is supposed to support. Separate a teaching example from a forecast, recommendation, or causal claim.

Eligible universe

Name the population, audience, market, placement set, page set, lead universe, or respondent group that could have entered the result.

Baseline and counterfactual

Show the prior period, matched context, holdout, model baseline, or explicit statement that no counterfactual was measured.

Outcome quality

Define the counted outcome, denominator, quality filter, duplicate rule, conversion window, lead status, sales follow-up status, survey field dates, or matchback rule.

Transfer boundary

List the conditions that must remain similar before the case can inform another decision: audience, channel, price, creative, destination, timing, tracking, and comparison design.

Common overreads

Success story as proof

A useful result is written as if it proves repeatable lift, even though the comparison and transfer conditions are narrow.

Extreme cell as lesson

The strongest placement, market, creative, or audience slice becomes the headline without showing denominator, noise, or minimum cell size.

Mechanism drift

A case that demonstrates one failure mode is reused to explain different outcomes in settings where the mechanism may not apply.

Platform halo

A result from one channel, package, or measurement environment is treated as proof for broader media value.

Outcome substitution

Observed visits, leads, brand recall, or matched conversions are described as business impact without the needed outcome-quality checks.

Missing ordinary case

The case shows the memorable result but not the routine cases that would reveal whether it is typical or exceptional.

Rewrite the claim

Overbroad wording	Cleaner wording	Evidence needed to go stronger
"This case proves the strategy works."	"This case documents a successful result under these conditions."	Preselected comparison, outcome quality, uncertainty, and repeated cases.
"The campaign drove demand."	"The campaign produced observed response; lift depends on the comparison design."	Holdout, matched baseline, or calibrated model evidence.
"This is a typical buyer journey."	"This journey illustrates one path; typicality depends on the broader eligible universe."	Journey distribution, denominator, and source-path disclosure.
"The winning slice should get more budget."	"The slice outperformed in this readout; action depends on minimum size, mix, and uncertainty."	Stable cell size, repeated performance, and comparable delivery conditions.
"The same result should happen again."	"The case can inform the next test if audience, timing, creative, destination, and measurement conditions are similar."	Replication plan, transfer checklist, and decision threshold.

Meeting questions

What broader claim is this case being asked to support?
Was the case selected because it is typical, vivid, recent, successful, extreme, or easy to measure?
What denominator would tell us whether this case is common or rare?
What comparison would show whether the result was caused by the campaign, setting, timing, or audience?
Which conditions must remain similar before the lesson can travel?
What wording remains true if the case does not repeat?

Use with

Pair this checklist with the anecdote and exemplar checklist when one vivid example may be doing too much evidence work, the campaign baseline comparison checklist when observed response is being promoted into lift, the campaign readout QA checklist when a finished report needs evidence-level language, the outcome quality scorecard before outcome volume becomes value, the evidence-to-claim language matrix when a summary sentence needs narrower wording, and the case-study library when a reader wants worked examples of tempting but weak comparisons.

Takeaway

A credible case study makes the useful lesson easier to inspect and the transfer limit harder to miss. Let cases teach mechanisms, questions, and warning signs. Save broad performance claims for evidence that shows the pattern can travel.