To:  sbaker@odu.edu

From:  Thomas Meyer
tmeyer@ph.vccs.edu
276 656-0283
Patrick Henry Community College

Subject:  Statistics - w/  Dr.Spencer Baker - Homework Assignment #4, Ch 15 - Problem 22, page 402.

Date: March 28, 2004

Use the following algorithm:

1.  Get the data

2.  Manipulate the data

To conduct the Chi-square test:

Having loaded the data
Click Analyze menu and choose Descriptive Statistics

select Crosstabs...

Move the variable "Recruitment Strategy" into the row;
Move the variable "Donate Blood" into the column.
Click Statistics and mark Chi-square.
Click Continue box

Click OK.

3.  Do something with the data

Right-click the output
Select copy object
Paste the copied object into FrontPage  (Before you paste the object, right-click and read the "results coach")
Save your work

 

Note:  When the variable you are testing is dichotomous (such as gave blood, did not give blood, is a democrat, isn't a democrat) use the chi-square as a test statistic, or use the binomial distribution.

When the variable you are testing is continuous (such as intelligence, persistance, emotive level, etc.) use the t-test statistic to determine whether outcomes differ from what could have been predicted from chance alone.

 

Question:
Use the SPSS data bank provided with this book to conduct a X2 (chi-square) test of independence analysis of the data contained in the data file donate.sav.  Conduct an analysis to answer the question.  "Is the recruitment strategy (recruit; 1= control,2 = information session, 3 = information session and empathic video) related to the number of people who donated blood (donate;0 = did not donate blood, 1 = donated blood)?"  Given the result of your analysis, what answer would you provide for this question?

Answer:

 

 

Alpha is .05.  The Person Chi-Square 2-sided test statistic is .026, which is less than the alpha value of .05.  Thus the recruitment strategies resulted in different proportions of people who gave blood.  The information session & video strategy resulting in 12 donations from 40 donors exceeded the information session only strategy that produced 6 donations from 40 donors. This difference was more than might have been expected by chance alone.

 

filename: StatHW3Ch15Prob22page402TomMeyer.doc

Tom Meyer

Thomas Meyer