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Date:         Thu, 5 Dec 1996 08:30:38 -0800
Reply-To:     hmaletta@overnet.com.ar
Sender:       "SPSSX(r) Discussion" <SPSSX-L@UGA.CC.UGA.EDU>
From:         "Hector E. Maletta" <hmaletta@OVERNET.COM.AR>
Subject:      Re: Calculating (& saving) a mean value across cases
Comments: To: Jeremy Miles <J.N.V.Miles@DERBY.AC.UK>

Jeremy Miles wrote: > > At 14:41 04/12/96 -0500, Andrew Gotowiec wrote: > >In SPSSWIN v6.1.2, is there any way to calculate a mean value for a > >variable across cases and then save that value for use in subsequent > >analyses? > >Any help would be gratefully received. > >andy > > > > > > COMPUTE meanvar = MEAN(var1, var2, var3) . > > Or available in transform, compute. > > Hope that helps. > ============================================================= > Jeremy Miles, Psychology Division, Derby University, DE3 5GX > Work: 01332 622222 x. 2173 j.n.v.miles@derby.ac.uk > =====================No Space for a Joke=====================

Jeremy, I'm afraid you missed the point of the question. Your answer gives a mean across variables (for every case), whilst the question was a mean across cases (for a given variable).

The only way I find to do the trick is through AGGREGATE. First, you agggregate the cases into one or various groups, and define a new variable at the aggregate level which is the average of some original variable. This gets saved in a new (aggregated file) with only one or more "super-cases" which represent aggregations of the original cases. Second, you assign that mean to every individual case through MERGE FILES /ADD VARIABLES considering the aggregate file as a TABLE. The syntax for a simple case would be:

GET FILE=DATA.SAV. SORT CASES BY ID. COMPUTE X=1. AGGREGATE /OUTFILE=MEANS.SAV/BREAK=X /MEANY=MEAN(Y). MATCH FILES /FILE=DATA.SAV / TABLE=MEANS.SAV/BY X.

This example computes only an overall mean for the variable Y, because the aggregating variable X is a constant (X=1) for all cases. If the means of subgroups are desired, the only modification would be using some grouping variable Z instead of X.

Hope this helps.

Hector Maletta Dept of Social Science Universidad del Salvador Buenos Aires, Argentina


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