The first question the experimenter was interested in was whether background noise has any effect at all. That is, whether the null hypothesis: µ

Analysis of variance can be used to provide a significance test of the null hypothesis that these three population means are equal. If the test is significant, then the null hypothesis can be rejected and it can be concluded that background noise has an effect.

In a one-factor between- subjects ANOVA, the letter "a" is used to indicate the number of levels of the factor (a = 3 for the noise intensity example). The number of subjects assigned to condition 1 is designated as n