View Full Version : statistical evidence of difference between detectives

04-08-2008, 10:07 PM
The captain is trying to find out which detective solves more cases per month. A random sample is run over 6 months. Detective A solves 3.5 cases per month with a SD of 0.5. Detective B solves 4.0 cases a month with a SD of 0.7. Assume equal poplulation variances.

Is there statistical evidence that the average number of cases solved per month differs at a significance level of 0.05?
What can you say about the P-value?
Construct a 95% confidence interval for the mean difference in cases solved.

A) do you just run a test for a population mean for both detectives and compare if they fall in the signifigance level?

B)would you say P(>1.645) as the significance level is a 90% confidence interval?

C) I understand how to obtain the range; however, what is the mean difference? Is it 4.0 - 3.5 = 0.5?

04-09-2008, 10:54 AM
The distribution of the individual means will do you little good.

H_{0}: Solve_{A} = Solve_{B} \implies Solve_{A} - Solve_{B} = 0

H_{a}: Solve_{A} - Solve_{B} \neq 0