READINGS
 		 GUIDE 1: ISSUES IN MODELING
GUIDE 2: TERMINLOGY
GUIDE 3: THE LOWLY 2 X 2 TABLE
GUIDE 4: BASICS ON FITTING MODELS
GUIDE 5: SOME REVIEW, EXTENSIONS, LOGITS
GUIDE 6: LOGLINEAR & LOGIT MODELS
GUIDE 7: LOG-ODDS AND MEASURES OF FIT
GUIDE 8: LOGITS,LAMBDAS & OTHER GENERAL THOUGHTS		 OVERVIEW
 

 
 
EDF 6937-01       SPRING 2009
THE MULTIVARIATE ANALYSIS OF CATEGORICAL DATA
EXERCISE 1: 
TERMINOLOGY, ODDS RATIOS, AND DEGREES OF FREEDOM 
Susan Carol Losh
Department of Educational Psychology and Learning Systems
Florida State University

 
 
 
THIS EXERCISE IS DUE THURSDAY FEBRUARY 5 AT CLASS. WE WILL DISCUSS IT BEFORE YOU TURN IN YOUR EXERCISE.

If you can't attend class February 5, please see that I receive your exercise by TWO P.M. Thursday February 5.

Please remember NO EMAIL ATTACHMENTS!

You may email me your answers as text in an email. That is OK.
Or fax to 644-8776. (Attention: Dr. Susan Carol Losh)
Or place in my EPLS mailbox.
Or mail to: Dr. Susan Carol Losh, Educational Psychology and Learning Systems, Florida State University, Tallahassee FL 32306-4453.
 

This exercise will give you some preliminary experience with three way cross-tabulation tables. We are starting out "easy" because each of the three variables has only two categories or values. The data (n = 3391) are aggregated from two separate NSF Surveys of Public Understanding of Science and Technology (2001 and 2006). The table uses the following three variables:

GENDER: 1 = Male  2 = Female  For purposes of this assignment, consider the value "male" to be a "success".

EARTHDUM:  1= Correct answer, the earth goes around the sun  0 = any other answer. For purposes of this assignment, consider the value "earth goes around the sun" to be a "success".

YEAR: 2001 or 2006. For purposes of this assignment, consider the value "2006" or "correct" to be a "success".

This 2 X 2 X 2 table looks as follows:
 

 
2001 
      
   
 2006
PLANET QUESTION
MALE
FEMALE
 
  
 MALE 
FEMALE
  
EARTH GOES AROUND SUN (CORRECT)
104
282
386
  
146
305
451
OTHER
 649
538
1187
  
652
715
1367
 
753
820
 1573
  
798
1020
1818

USE THE TABLE ABOVE TO ANSWER THE FOLLOWING QUESTIONS.
PLEASE BE SURE TO ANSWER ALL DESIGNATED PARTS OF A QUESTION.
PLEASE SHOW YOUR WORK ON ALL QUESTIONS.

1. (1 point)  FOR THE TOTAL SAMPLE, what is the odds on GENDER--MALE:FEMALE?

2. (1 point) FOR THE TOTAL SAMPLE, what is the odds on YEAR, 2006--2001?

3. (1 point) FOR THE TOTAL SAMPLE, what is the odds on the PLANET question--CORRECT:OTHER?

4. (1 point) What is the FIRST ORDER CONDITIONAL ODDS for each category of GENDER for "PLANET"--CORRECT:OTHER?

5. (1 point) What is the FIRST ORDER CONDITIONAL ODDS for each category of YEAR for "PLANET"--CORRECT:OTHER?

6. (1 point) FOR THE TOTAL SAMPLE, what is the second order odds ratio for YEAR and PLANET?
(1 point) Do you think there is an association between year and answers to the Planet science question? Why or why not?

7. (1 point) FOR THE TOTAL SAMPLE, what is the second order odds ratio for YEAR and GENDER ?
(1 point) Do you think there is an association between gender and year? Why or why not?

8. (1 point) FOR THE TOTAL SAMPLE, what is the second order odds ratio for GENDER and PLANET?
(1 point) Do you think there is an association between gender and answers to the Planet science question? Why or why not?

9. (1 point) FOR THE TOTAL SAMPLE, what is the third order odds ratio for GENDER, YEAR, and PLANET?
(2 points) How do you interpret this odds ratio IN WORDS? (HINT: Try calculating some percentages and see if that gives you clues about interpreting the results)?
(1 point) Do you think there is a statistical interaction among gender, year and the science question?
(1 point) Why or why not?

10. (1 point) How many TOTAL degrees of freedom are there in this 2 X 2 X 2 table?

11. (1 point) If we fix the total case base (i.e., constrain the model case base to equal the observed case base), how many degrees of freedom ARE LEFT?

12. Suppose you have a FULLY SATURATED model for GENDER X YEAR X PLANET.

(1 point) Which parameters have you fixed in this case?
(1 point) What is the degrees of freedom associated with this fully saturated model?
 
 
 
READINGS AND ASSIGNMENTS

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Susan Carol Losh
January 28 2009