Content Validity Ratio (CVR)

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Reliability (legacy hub)

Independently verified. Every statistic this test reports has been re-derived against an independent reference — never the library the pipeline itself calls — the rendered output was read back in a browser, and the result is locked with a committed regression suite.

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Content Validity Ratio — Lawshe's index of how essential experts judge each item to be.

CVR runs from −1 to +1 based on how many experts call an item 'essential'; items below a panel-size-dependent critical value are candidates for removal.

Worked example

Which items do experts consider essential?

Twelve experts rated each item as essential / useful / not necessary; Lawshe's CVR is computed per item.

Result

15 of 20 items exceeded the critical CVR (.56 for 12 experts) and were retained.

How you'd report it (APA)

Fifteen items met Lawshe's CVR threshold (> .56), supporting their retention.

Try it yourself: Load this ready-made sample and follow the run above.

When to use it

  • Lawshe's essential-item method
    Experts judge each item essential / useful / not necessary and you want the ratio favouring 'essential'. e.g. 12 experts, 20 items.
  • Panel-size-calibrated retention
    CVR is compared against a critical value that depends on how many experts rated — built into the decision.

When NOT to — use instead

Assumptions (and what to do if they fail)

Critical value matched to panel sizehigh

Check: The CVR cut-off falls as the panel grows (e.g. ≈ .56 at 12 experts); use the value for your actual n.

If violated: Applying the wrong critical value keeps bad items or drops good ones.

Three-category essentialness formatmedium

Check: Items are rated essential / useful-but-not-essential / not necessary — CVR is defined for exactly this format.

If violated: A different rating format does not map onto Lawshe's formula.

Independent, qualified expertsmedium

Check: Experts judge essentialness without conferring.

If violated: Shared judgements inflate the essential count and the ratio.

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