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Statistical Software > SPSS II > Self-Assessment Test

PASW Statistics Workshop Placement Self-Assessment Test

Doing the following exercise will help you decide which PASW Statistics workshop is appropriate for you. If you have a lot of difficulty doing these tasks, or need a great deal of help to do them, sign up for the PASW Statistics I - Introduction class. If you can do these tasks with little or no help, you are ready for the PASW Statistics II - Data Management class.

The file lowbwt2.dat contains data on 189 subjects. Eight variables were measured on each subject to help identify risk factors associated with giving birth to a baby with low birth weight (weighing <2500 grams).

NOTE: These data come from Hosmer and Lemeshow (2000) Applied Logistic Regression: Second Edition. These data are copyrighted by John Wiley & Sons Inc. and must be acknowledged and used accordingly. For purposes of this exercise, a few missing data points have been introduced.

First, download the datafile. Click on lowbwt2.dat, then choose Save As on the File menu.

• Identification Code
• Low Birth Weight (0 = birth weight ge 2500g, 1=birth weight < 2500g)
• Mother's Age (in years, 0 indicates missing value)
• Mother's weight at last menstrual period (in lbs, 999 indicates missing value)
• Race (1=White, 2=Black, 3=Other)
• Smoking Status During Pregnancy (1=Yes, 0=No)
• History of Premature Labor (0=None, 1=One, etc.)
• History of Hypertension (1=Yes, 0=No)
• Presence of Uterine Irritability (1=Yes, 0=No)
• Number of Physician Visits during the First Trimester (0=None, 1=One, etc.)
• Birth Weight (in grams, 0 indicates missing value)

1. Read the lowbwt2.dat data file into an PASW Statistics data file.  Assign appropriate variable and value labels, and change the missing value codes in the data into PASW Statistics missing values.

2. Run Frequencies or Means on each variable, as appropriate. (i.e. choose the appropriate procedure for each variable.)

3. Look at the output and check that all results are reasonable, and that missing values have been handled properly.

4. Save the PASW Statistics data file.

5. Exit PASW Statistics.

6. In a new PASW Statistics session, open the saved PASW Statistics datafile, and run a Crosstabulation on the variable Low Birthweight by Smoking Status during pregnancy.  What proportion of smokers' babies were low birth weight compared to the proportion of non-smokers' babies?

7. Next, run Means to compare the birth weight of babies born to mothers who smoked or didn't smoke.

8. Interpret the results. Are they reasonable?