Question

study of the effects of smoking on hours of sleeping classifies subjects as nonsmokers, moderate smokers, or heavy smokers. The investigators interview a sample of 80 people in each group. Assume all the conditions for ANOVA are met. Identify the degrees of freedom of numerator (df1) and denominator (df2) for the one-way ANOVA F test statistic for comparing the mean hours of sleep among these groups.

Answer 1

df1=2

df2=77

Explanation:

We have a=3 groups: nonsmokers, moderate smokers, and heavy smokers.

For each group, N=80 people are interviewed.

The degrees of freedom of numerator (df1) are calculated as the number of groups less one. Then:

`df1=a-1=3-1=2`

The degrees of freedom of denominator (df2) are calculated as the number of individuals in each group less the amount of groups. Then:

`df2=N-a=80-3=77`