Question

Sample weights (in pounds) of newborn babies born in two adjacent counties in western Pennsylvania yielded the following data:

n = 53 m = 44

X = 6.8 Y = 7.2

S2 = 5.2 S2 = 4.9

a) Consider a test of the hypothesis that the mean weight of newborns is the same in both counties. What is the resulting p value? How would you express your conclusions to an intelligent person who has not yet studied statistics?

b) Assuming that the population variances are equal.

1. Would you reject the null hypothesis at the 5 percent level of significance?

2. How does the p value compare with the one previously obtained?

Answer 1

a)

Here we need to use independent sample t test. Hypotheses are:

Following is the output of t test generated by excel:

The p-value is:

p-value = 0.3844

Since p-value is greater than 0.05 so we fail to reject the null hyothesis.

Conclusion: One cannot conclude that the mean weight of newborns is the same in both counties.

b)

Following is the output of t test generated by excel:

The p-value is:

p-value = 0.3857

Since p-value is greater than 0.05 so we fail to reject the null hyothesis.

Conclusion: One cannot conclude that the mean weight of newborns is the same in both counties.

2:

Both p-values are approximately same.