Assignment 6

Directions: Please provide all answers using complete sentences. You are required to show your work on any item that involves calculations.

1.	Below is a list of the top nine longest serving U.S. Supreme Court Justices, along with the current Chief Justice of the court:

Name			Length of Service (in years)
William O. Douglas		  36 
Stephen Johnson Field		  34
John Paul Stevens		  34
John Marshall			  34
Hugo Black			  34
John Marshall Harlan		  33
William J. Brennan		  33
Joseph Story			  33
James Moore Wayne		  32
John Roberts 			  11

Please provide the following information (1 pt. each):

a. M years of service 
b. SD years of service
c. Probability of observing the term length of John Roberts
 
2.	Please briefly explain what a power analysis is and why it is conducted.

3.	What is standard error of the mean (SEM)? Please briefly describe whether it is better to have a large or small SEM, and why.

4.	Using variables of your choice, please provide one specific original (i.e., something discussed neither in class nor the textbook) example of both a null and an alternative hypothesis. Please include the scientific notation for each hypothesis in your answer. (2 points)
5.	With respect to significance testing, please explain the difference between a Type I and Type II error.  

6.	If the calculated p-value for a given significance test is greater than .05 we _________ the null; if the calculated value of a significance test is equal to or greater than the critical value for that significance test, we _________ the null. (Both answers must be correct to earn full credit)
7.	Please explain the difference between a one-tailed and a two-tailed test of significance (Tip: Although you are not required to do so, feel free to sketch a picture to complement your answer). When it comes to significance testing, which is more statistically rigorous? Why?