Answer: 3 treatments and 21 subjects were participating in the study .
Step-by-step explanation:
Let the number of treatments be k and the total number of subjects participating in the study be n.
Then , the df for numerator of F-ratio = k-1
df for denominator of F-ratio = n-k
Given : A researcher reports an F-ratio with df = 2, 18 from an independent-measures research study.
Based on the df values, we have
k-1 = 2 and n-k= 18
If [tex]k-1=2\\\Rightarrow\ k=2+1=3[/tex]
Then, [tex]n-3= 18\Rightarrow\ n=18+3=21[/tex]
Therefore , 3 treatments were compared in the study and 21 subjects were participating in the study is 21.
