Date:         Fri, 23 Feb 2007 13:33:32 -0800
Reply-To:     Dennis Deck <DDeck@rmccorp.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Dennis Deck <DDeck@rmccorp.com>
Subject:      Re: Comparing samples on SPSS
In-Reply-To:  <12B8F708F6A7E94AAD1EFF9FC1B4B341022E8525@AZDESGOVEX001.azdes.gov>
Content-Type: text/plain; charset="us-ascii"

Rereading the original post I realize that the intended question was
probably: "How can I see whether the two samples differ on each of these
categorical variables".  A conventional approach would be to use T-TEST
for continuous variables (age) and CROSSTABS for categorical variables
(marital status).  With such large N's (9K-10K), even trivial
differences will likely be significant so you may want to also calculate
effect sizes or standardized differences.

However, in many fields the researcher must compare naturally occurring
groups which typically differ on multiple variables.  Propensity Score
Analysis (generally using LOGISTIC) offers a useful multivariate
strategy for modeling the overall differences in the groups and
adjusting for these differences in subsequent analyses.  If you have two
samples drawn in different years or from different populations and you
want to say something about any differences adjusting for sample
characteristics, this would be an appropriate approach.

Dennis Deck, PhD
RMC Research Corporation
ddeck@rmccorp.com

-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Dennis Deck
Sent: Friday, February 23, 2007 1:05 PM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: Re: Comparing samples on SPSS

What Anthony describes is essentially a step in Propensity Score
Analysis.  The approach encourages you to carefully model the sample
differences.

You can save the predicted score from the logistic regression and use it
in subsequent substantive analyses where you want to adjust for sample
differences (eg, as a covariate, weight, matching variable, etc).

Be sure to properly handle your categorical predictors.

Dennis Deck, PhD
RMC Research Corporation
ddeck@rmccorp.com


-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Eugenio Grant
Sent: Thursday, February 22, 2007 4:48 PM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: Comparing samples on SPSS

Hello to all



I have results form a sample of 10.000 interviews for a series of
variables:



Age (1,2,3,4...99)

Marital Status (Single, married, divorced, etc)

Persons in home (1,2,3,4,5,6, more)

Income Level (High, Medium, Low)



And results form another sample of 9.000 interviews.



How can I establish if both samples are correctly taken, in other words,
if
they are comparable with each other or not?



Regards,

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