Question

A researcher studied the time between initial submission and publication of articles in two journals. For 292 articles published in journal​ A, the mean length of time was 18 months, with a standard deviation of 8 months. For 233 articles published in journal B the mean length of time was 30 ​months, with a standard deviation of 14 months. Create a​ 90% confidence interval for the difference in mean​ delay, μB−μA. Do not assume that the variances are equal.

The confidence interval is ( _ , _ )

​(Round to two decimal places as​ needed.)

Answer 1

The statistical software output for this problem is :

Two sample T summary confidence interval:
μ₁ : Mean of Population 1
μ₂ : Mean of Population 2
μ₁ - μ₂ : Difference between two means
(without pooled variances)

90% confidence interval results:

Difference	Sample Diff.	Std. Err.	DF	L. Limit	U. Limit
μ1 - μ2	12	1.0297474	349.71875	10.301717	13.698283

The confidence interval is ( 10.30 , 13.70)