What is the standard error of the mean difference Use the in

What is the standard error of the mean difference?

Use the information from the t-test table only. Round your answer to 2 decimals

Variable

Mean

SD

n

Prescribed pain relief medication

68.2

12.11

25

Over-the-counter pain reliever

62.7

15.36

25

t-test

t

df

Mean Difference

Standard error of the mean difference

Sig.

99% CI of the difference

Lower

Upper

1.38

48

5.5

???

0.174

-5.27

16.27

Solution

Calculating the standard deviations of each group,              
              
s1 =    12.11          
s2 =    15.36          
              
Thus, the standard error of their difference is, by using sD = sqrt(s1^2/n1 + s2^2/n2):              
              
n1 = sample size of group 1 =    25          
n2 = sample size of group 2 =    25          

Also, sD =    3.911939161   [ANSWER]