A researcher has developed a new drug designed to reduce blo

A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group and received the new experimental drug. The other 23 subjects were assigned to the control group and received standard, well-known treatment. The Researcher should use which value for degrees of freedom when calculating statistics from the results?

A. Use the smaller value, 20, chosen from the two options 20 and 22.

B. Use the larger value, 22, chosen from the two options 20 and 22.

C. Use the smaller value, 21, chosen from the two options 21 and 23.

D. Use the larger value, 23, chosen from the two options 21 and 23.

Solution

The degrees of freedom of each group are

df1 = n1 - 1 = 21 - 1 = 20
df2 = n2 - 1 = 23 - 1 = 22

Thus, we use the more conservative, the smaller degrees of freedom:

OPTION A. Use the smaller value, 20, chosen from the two options 20 and 22. [ANSWER, A]