Answer: 10
Step-by-step explanation:
We know that the degree of freedom for two sample with sample sizes [tex]n_1[/tex] and [tex]n_2[/tex] is given by:-
[tex]df=n_1+n_2-2[/tex]
If sample sizes are same , then [tex]df=n+n-2=2n-2[/tex] (1)
Given : An independent-measures study comparing two treatment conditions produces a t statistic with df = 18.
Then, from (1) , we have
[tex]2n-2=18\\\\\Rightarrow\ 2n=20\\\\\Rightarrow\ n=10[/tex]
Hence, the number of participants were in each of the samples =10
