* Univar.sps.
* Sample SPSS descriptive statistics example. Replicates examples in handout.
* This program is really quite short, but these painstakingly detailed
* comment lines stretch it out. Comment lines are very handy though
* if you are ever trying to figure out why you did something the way you did.
* Also, while I am giving you this program, this could all easily be done
* interactively using SPSS Menus. In effect, SPSS will generate most
* of this syntax for you.
* First, enter the data. Normally I would create a separate data file, but for
* now I will enter the data directly into the program using the
* data list, begin data and end data commands.
data list free / X.
begin data.
100
150
200
250
250
250
250
325
325
400
end data.
* The formats command tells SPSS that X is measured in dollars.
* Not essential, but it helps make the display easier to read. This could
* also be done using the SPSS Data Editor. The Var Labels Command
* will also make the output easier to read.
Formats X (dollar8).
Var Labels X "Weekly Income".
* Next, run the frequencies command, indicating what stats I want.
* I used SPSS menus to generate the syntax for this command, but it
* could also be typed in directly.
FREQUENCIES
VARIABLES=x
/STATISTICS=STDDEV VARIANCE MEAN MEDIAN MODE SUM
/ORDER= ANALYSIS .
* In the output, notice that the variance and SD are bigger than what I had in
* my example.
* This is because SPSS assumes we are analyzing a sample, whereas
* in the the example I stated we had the entire population,
* hence SPSS uses a slightly different formula for its calculations. The
* difference between sample estimates and population parameters
* will be discussed in class.
* Now, here is how to run the problem when the data are already grouped
* in a frequency distribution.
* The variable WGT indicates how often the value occurs in the data.
data list free / X WGT.
begin data.
100 1
150 1
200 1
250 4
325 2
400 1
end data.
Formats X (dollar8).
Var Labels X "Weekly Income"/ Wgt "Weighting Var".
* The Weight command causes cases to be weighted by the # of times
* the value occurs.
Weight by Wgt.
* Now just run the frequencies again.
FREQUENCIES
VARIABLES=x
/STATISTICS=STDDEV VARIANCE MEAN MEDIAN MODE SUM
/ORDER= ANALYSIS .