Math 104

February 11, 2005

SPSS Assignment 3

This assignment is due February 23, but as noted below, most of it is very good review for the exam on February 18.

1. In the SPSS text, read Chapter 5.

Note: This chapter covers much of the same material as Chapters 3 and 4 in our text. There are some slight differences in terminology, which shouldn’t be too confusing.

On page 86-87: We aren’t using the SPSS text’s definition of “range.” We care about variance only as a step in calculating SD. (Also, notice that for standard deviation, the SPSS text uses “n-1” in the denominator; that is, its standard deviation is what we called SD⁺.) Finally, we won’t ever use “coefficient of variation.”

2. Turn in answers to these exercises from the “Statistical Concepts” section of Chapter 5, pp. 93-94: exercises 4, 5, 6, and all of 9.

[ Hints and suggestions: We’ll talk about 4 in class. On problem 5, recall that variance is SD squared. They have given you SD, and you can use that to compute variance—even if you suspect that it’s really SD⁺. For problem 9, please give the standardized scores to 2 decimal places, like 5.67. You might be able to get SPSS to do #9 for you, but it’s probably easier to do it by hand—and better practice. ]

3. Turn in answers to these “Data Analysis,” pp. 95-98: exercises 1, 4 (using gss.sav or gssnet.sav).

HINTS AND SUGGESTIONS (for the Data Analysis part)

In all of the problems in which you are asked for “descriptive statistics”, you should find the mean (average), median, mode, the quartiles, standard deviation, minimum, maximum. (Skip “range” if you like).

In all of the problems here the phrase “measures of central tendency” means the average (mean), median and mode.

In all of the problems here when you are asked to create standardized scores (z-scores) for a variable, the computer will add a new column of standardized values in the Data Editor window. These new columns will always be to the right of most of the other data columns, and you will usually not see them unless you go looking for them. These standardized scores do not need to be printed out (beware of printing large data windows!) but SPSS will use them in computing other things (such as histograms) which you do need to print out.

#1) In this problem make certain that you copy into your word-processor file: descriptive statistics (as described above) and histograms for each of the three variables given to you.

#4c) To answer this question you are to make and copy a histogram of “tvhours” (the unstandardized variable) and compare it with the histogram from part (b).

#4f,g) In these parts you should compute the desired results by hand using the average and SD for the variable “tvhours”. You will find the average and SD printed next to the histogram that you made in part (c) above.

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