Scheffé crítico aprox
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Scheffé critical value calculator helps determine the statistical threshold for specific group comparisons after a significant ANOVA. It uses the formula √[(k−1)·F·MSW·(1/n₁ + 1/n₂)], where k is the number of groups, F is the critical F-value, MSW is the within-group mean square, and n₁/n₂ are the compared sample sizes.
This tool calculates the minimum difference required between groups to be statistically significant, adjusting for multiple comparisons. It reduces the risk of false positives in post-ANOVA tests.
Use this calculator when comparing specific contrasts after an ANOVA. For instance, in medical studies to check if a new drug is significantly better than two existing treatments. Avoid using it for casual comparisons between all group pairs.
Caution: the formula assumes normally distributed data and homogeneous variances between groups. Small samples may reduce result accuracy. Always validate ANOVA assumptions before proceeding.
Frequently asked questions
How does Scheffé analysis differ from Tukey test?
While Tukey compares all group pairs, Scheffé is ideal for planned specific contrasts. Scheffé has higher statistical power for non-pairwise comparisons but is more conservative.
What if sample sizes are unequal?
The formula accounts for different sample sizes (n₁ and n₂). No need to balance samples, but large disparities may affect accuracy.
Should I always use Scheffé after ANOVA?
No. Use Scheffé only when you have pre-defined specific contrasts. For random multiple comparisons, Tukey or Bonferroni tests are more appropriate.
How to interpret the critical value?
If the difference between two means exceeds the Scheffé critical value, that difference is statistically significant.