A) Treat the data as if the scores are from an independent-measures study using
ID: 3135395 • Letter: A
Question
A) Treat the data as if the scores are from an independent-measures study using two separate samples, each with n = 8 participants. Compute the pooled variance, the estimated standard error for the mean difference, and the independent-measures t statistic. Using a two-tailed test with a = .05 , is there a significant difference between the two sets of scores?
B) Now assume that the data are from a repeated-measures study using the same sample of n = 8 participants in both treatment conditions. Compute the variance for the sample of difference scores, the estimated standard error for the mean difference and the repeated-measures t statistic. Using a two-tailed test with a = .05 , is there a significant difference between the two sets of scores?
Students / Following Nights with above average sleep / Following Nights with below average sleep
A/ - 10/ - 13
B/ - 8/ - 14
C/ - 5/ - 13
D/ - 5/ - 5
E/ - 4/ - 9
F/ - 10/ - 6
G/ - 11/ - 6
H/ - 3/ - 6
Explanation / Answer
answer of a)t=(mean1-mean2)/(sp/n1/2) and sp2=((n1-1)s12+(n2-1)s22)/n and n=n1+n2-2
sp2=12 , standard error=sp/n1/2=12/sqrt(14)=3.21
t=|(9.71-14.29)|/3.21=1.43
t-critical(.05,14)=2.14
t-critical 2.14 is more than t-calculated 1.43 so there is no significant difference between two score
answer b) t=|d-|/(sd/n1/2)=|-2|/sqrt(sd2/n)=2/1.6475=1.21
standard error=sd/n1/2=sqrt(sd2/n)=1.6475
t-critical=t(.05,7)=2.36
t-critical 2.36 is more than t-calculated 1.21 so there is no significant difference between two score
x y d=x-y 10 13 -3 8 14 -6 5 13 -8 5 5 0 4 9 -5 10 6 4 11 6 5 3 6 -3 mean= 7 9 -2 var=s2= 9.714286 14.28571 21.71429 n= 8 8 8Related Questions
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