A multiple-comparison correction known as the Bonferroni correction is applied when several dependent or independent statistical tests are run concurrently (since while a given alpha value alpha may be appropriate for each individual comparison, it is not for the set of all comparisons).
The alpha value must be decreased to reflect the amount of comparisons being made in order to prevent a large number of bogus results. The Bonferroni correction is generally obtained by dividing the level of significance by the number of comparisons made.
Given the values of level of significance and number of comparisons (n) the Bonferroni Correction Calculator below calculates the adjusted level of significance.
Adjusted α: 0.01250
Interpretation: If you conduct 4 comparisons, only reject the null hypothesis of each comparison if it has a p-value less than 0.01250.