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Lawshe's content validity ratio (CVR) calculator

In Lawshe’s method (1975), each judge classifies each item as "essential", "useful but not essential" or "not necessary". The content validity ratio (CVR) tells you whether agreement that the item is essential is higher than chance. Paste the answers from Excel: one row per item and one column per judge, with 1 for "essential" and 0 for the other two options. You can also paste the words as they are.

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How it’s calculated

For each item, count how many judges marked it as essential (ne) out of N judges.

CVR = (ne − N/2) / (N/2). It goes from −1 (no judge considers it essential) to 1 (all of them do).

The critical value depends on the number of judges. It uses the table recalculated by Ayre and Scally (2014) with the exact binomial distribution, which fixes errors in Lawshe’s original table.

The Tristán-López (2008) modification, common in Latin America, is also shown: CVR' = ne / N, with a minimum of 0.58.

The instrument’s content validity index (CVI) is the mean CVR of the items you keep.

How to read the result

  • An item is valid if its CVR is equal to or above the critical value. With 10 judges the minimum is 0.80 (9 of 10 must say "essential"); with 8, 0.75; with 7 or fewer, all of them.
  • With fewer than 5 judges no item can reach the minimum, even if everyone marks "essential". For Lawshe, 8 judges or more is better.
  • If your university asks for the Tristán-López version, use the CVR' column: items are accepted from 0.58.
  • Revise or remove the items that fall short, and recalculate the CVI with the ones you keep.
Next stepCronbach’s alpha calculatorAfter expert judgment comes the pilot test: calculate reliability with Cronbach’s alpha.Step-by-step guideAiken's V, Lawshe, CVC or binomial test: which one to use to validate your instrumentAiken's V vs Lawshe's CVR vs Hernández-Nieto's CVC vs the binomial test: how judges answer, the formula, an example and the cut-off for each.

Frequently asked questions

How many judges do I need for Lawshe?
At least 5, but with 5, 6 or 7 judges all of them must mark "essential". From 8 judges one disagreement is allowed. If you have few judges, Aiken’s V is usually a better fit.
Why doesn’t the critical value match Lawshe’s table?
The original 1975 table had calculation errors. Ayre and Scally (2014) recalculated it with the exact binomial, and that is the one recommended today. With 10 judges, for example, the original table said 0.62 and the corrected one says 0.80.
What is the Tristán-López CVR?
A modification proposed in Mexico in 2008: CVR' = ne / N, with a fixed cut-off of 0.58 that doesn’t depend on the number of judges. Many Latin American theses use it. Cite the version you applied.
What if my judges used a 1 to 4 scale?
Then use Aiken’s V, Hernández-Nieto’s CVC or the content validity index (CVI), which work with rating scales.

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