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Date:         Fri, 7 Jul 2006 11:41:35 -0400
Reply-To:     Joseph Teitelman temp2 <cmtemp2@pgahq.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Joseph Teitelman temp2 <cmtemp2@pgahq.com>
Subject:      Re: PPS sampling
Comments: To: Cathal McCrory <Cathal.McCrory@esri.ie>
Content-Type: text/plain; charset=US-ASCII

You are describing a systematic sampling design. A PPS sampling design
means a sample with probabilties proportional to size.
They are entirely distinct sampling designs. Whether you wish to choose
one of these sampling methods is dependent upon various factors.  I
would suspect that in your case you can use systematic sampling

>>> Cathal McCrory <Cathal.McCrory@esri.ie> 7/7/2006 11:05 AM >>>
I have the enrolment numbers for 3200 schools and I want to select
13,000
pupils from within these schools on a PPS basis. For example:

                        Pupil                   Cumulative
School                  Enrolment               Population
1                       116                     116
2                       163                     279
3                       232                     511
4                       204                     715
5                       274                     989
6                       188                     1177
7                       210                     1387
8                       407                     1794
9                       298                     2092

I want to generate a random start within SPSS and select every 4th
pupil
from within the cumulative population total (rather than a set number
of
cases) and have the program iterate until I have drawn my sample of
13,000.
I was wondering whether anyone could give me any pointers (to existing
routines) or offer any guidance on this. Many thanks.