Question

A retrospective study of 140 pairs of twins was performed. The twin pairs each had one male child and one female child. Their birth weights were studied to determine if the male twin was consistently heavier.

The difference in weights was calculated by subtracting the female weight (in ounces) from the male weight (in ounces):

d=xm−xfd=xm-xf

After looking at 140 pairs of twins, the study finds the 95% confidence interval for the mean difference of weights (in ounces) is:

-1.6 < μdμd < 2.8

Can we be reasonably sure that the male twins are heavier than the females?

• Yes
• No

Why or why not?

Answer 1

we get a 95% confidence interval for difference of mean weights as -1.6 to 2.8 . And this interval also contains 0 . which means , $\mu_d$ can be 0 , that is mean weights of both male and female child can be equal , So we cannot say that male twins are heavier than the females