Question

PLEASE PICK ONE OF THE OPTIONS BELOW FOR THE ANSWERS

Assume a researcher is interested in the effect of weight on a number of adverse events in his new clinical trial. Assume the following table represents the weights (kg) for a SRS of individuals in both arms of the study.

Placebo

76.5

64.7

67.8

65.2

74.6

80.1

64.8

Intervention

80.7

78.6

76.4

78.3

A) Calculate the standard error for the difference in weight between the two arms of the study.

B) Calculate the pooled standard error for the difference assuming equal variances.

Choose the most appropriate option

		OPTION 1 A) SE=3.28 B) SE=4.24
		OPTION 2    A) SE=2.58 B) SE=3.34
		OPTION 3    A) SE=2.85 B) SE=3.89

Answer 1

from above:

	Placebo		Intervention
x1    =	70.53	x2      =	78.50
s1    =	6.41	s2      =	1.76
n1    =	7	n2     =	4

standard error for difference: se=√(S21/n1+S22/n2)=

2.58

for pooled method:

Pooled Std dev Sp=√((n1-1)s21+(n2-1)*s22)/(n1+n2-2)=

5.3310

standard error se =Sp*√(1/n1+1/n2)=

3.34

Correct option is OPTION 2

A) SE=2.58

B) SE=3.34