# Project #24853 - Statistics

Posted: Mar. 3rd, 2014

Due: Mar. 11th, 2014, at the beginning of class

Total Points: 50pts

Be concise: if a problem asks for a definition or explanation, limit your answer to a sentence or two. Your homework must be neat, well organized and easy to read and follow. Please organize your work so that the problems are in order and clearly mark your final answers for each problem.

Textbook problems from “Essentials of Statistics for the Behavioral Sciences”

Chapter 9

#14 (5pts) When do we use a repeated measures t test?

Supplemental (45pts):

S1 (5pts) Suppose I am working with an independent sample t test, I’ve gotten ðÂ‘ ðÂ‘ 12=12 and ðÂ‘ ðÂ‘ 22=25, does it make sense to have a pooled variance ðÂ‘ ðÂ‘ ðÂ‘ÂðÂ‘Â2 to be 26? Make sure to state your reasoning.

S2 (13pts)A psychology department chair notices that the average number of student complaints the department receives per week is 1.4 times and a standard deviation of 1.6 times. He notices that the department has made some poor policy changes recently and wants to see if the number of complaints that the department receives has increased. He records the following number of complaints that came in per week for the past eight weeks:

2, 4, 3, 5, 4, 1, 1, 4

a) (2pts) Given the above information and a 5% alpha level, first choose an appropriate test to answer the question “if there are now more complaints”. Then list the hypotheses.

b) (3pts) Calculate the test statistics

c) (2pts) What conclusion can you make from your calculation? Make it clear that what your conclusion means regarding the research question.

d) (2pts) Compute the Cohen’s d coefficient and comment on the effect size.

e) (2pts) Write down the FORMAL conclusion (p value should be calculated).

f) (2pts) what is a Type I error and what is a Type II error in this context?

S3 (7pts)A psychology department chair notices that the average number of student complaints the department receives per week is 1.4 times. He notices that the department has made some poor policy changes recently and wants to see if the number of complaints that the department receives has increased. He records the following number of complaints that came in per week for the past eight weeks:

2, 4, 3, 5, 4, 1, 1, 4

a) (2pts) Given the above information and a 5% alpha level, first choose an appropriate test to answer the question “if there are now more complaints”. Then list the hypotheses.

b) (3pts) Calculate the test statistics

c) (2pts) What conclusion can you make from your calculation?

 S4 (10pts) A junior researcher at the Institute for the Obvious is studying whether eating good food makes people happy. He rounds up participants before lunch and asks them to fill out a standard measure of happiness. He then feeds them a delicious lunch and asks them to fill out the survey again. Based on the data below, what should the researcher conclude under 5% alpha level? Before Meal After Meal 4 5 7 8 8 8 5 6 6 6

 Subject Mathematics Due By (Pacific Time) 03/11/2014 09:00 am
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