* 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 .