BU Measures of Central Tendency & Poor Physical Health Essay

Problem # 1:  Measures of Central Tendency

Step 1: For each of the following 5 variables, choose the appropriate measure of central tendency based on: (1) the variables’ level of measurement; and (2) if a continuous (interval and ratio) variable, the shape of the distribution (skewed or symmetrical).  (Refer to Figure 4.8 in textbook).

Variables:

PHYSHLTH: Number of days of poor physical health in past 30 days

PILLOK:  Should the birth control pill be available to 14- to 16-year-olds?

OWNGUN: Are there any guns or revolvers in the respondent’s home?

GRASS: Does the respondent support legalization of marijuana?

SIBS:   How many brothers and sisters does the respondent have?

Step 2: Run the SPSS procedure for obtaining measures of central tendency:

• Select on the SPSS MenuàAnalyzeàDescriptiveàFrequencies
• A frequency dialog box will open.  Move the 5 variables into the box.  
• CLICKàStatistics
• Within the Statistics Dialog Box, choose MODE, MEDIAN and MEANàthen CLICKàCONTINUE
• Within the frequency dialog box, CLICKàOK
• Select on the SPSS MenuàAnalyzeàDescriptiveàFrequencies
• A frequency dialog box will open.  Move AGEKDBORN into the box.  
• CLICKàStatistics
• Within the statistics dialog box choose MEAN and STANDARD DEVIATION—then CLICKàCONTINUE
• In the frequency dialog box, CLICKà OK.

(Note: SPSS can produce descriptive statistics on multiple variables simultaneously)

Note: SPSS will produce a mode, median and mean for each variable EVEN if it is “not appropriate” given a variable’s level of measurement!

Note: Some people like to select CHARTS so that they have a visual presentation of the distribution.

Step 3: Write up your results. For each of the 5 variables: In a first sentence, indicate level of measurement and identify an appropriate measure of central tendency to use.  In a second sentence, report the results.

Problem # 2: Mean and Standard Deviation; Use of” Select Cases” option in SPSS

You are interested in exploring the differences between men and women in terms of the age at which they have their first child.  To do so, you will use the Select Cases option, for the male and the female respondents in the GSS2018 dataset and produce means and standard deviations for the ratio variable AGEKDBRN (age at which first child was born) for each sex: male and female.

Step 1: Run the SPSS procedure to Select Cases

a) SELECTING CASES BASED ON SEX

• From the SPSS Menu, choose DATA-à SELECT CASES
• When the dialog box opens, you will see that the top “button” is checked – “All Cases”.  You want to select the second button down “If Condition is satisfied” and then click “If”
• Now you are in another dialog box. Select and move the variable—SEX into the empty box. Using the keypad, click on the “=” sign and the “1”.  You want to end up with: SEX = 1 (You do this because for the variable SEX, 1 = Male and 2 = female.  You are telling SPSS you want to select only the males.
• ClickàContinue, and then Click OK
• Your data file now will only consider the males in the sample. If you look at the “data view” of the file, you will see that any case that isn’t a male (i.e., isn’t coded with “1” for SEX) is crossed out at the far left.  This means all the females are “crossed out” and will not be included in any procedure until you put the file back to “All Cases” again.
• From the SPSS Menu, choose DATA-à SELECT CASES
• When the dialog box opens, CHOOSE-à “Analyze all cases” (If you don’t do this, SPSS will continue to just look at just the SEX selected in the sample for any other procedure you do until you close the data file.)

b) PRODUCE MEAN AND STANDARD DEVIATION 

c)  NOW RUN SELECT CASES AND CHOOSE SEX = 2 (TO CHOOSE ONLY THE FEMALES IN THE SAMPLE) AND REPEAT b) above (produce means and standard deviations for the females)

d) TURN OFF SELECT CASES

Step 2: Write up your results. 

1. Write a brief analysis comparing male and female respondents’ ages at which they have their first child, reporting both means and standard deviations.  Why do you think from a social and physical context, there might be a difference in the mean age and variation around the mean age between men and women for when they tend to have their first child