June 2006 - EpiData-list - University of Manitoba Mailing Lists

Sumfreq and Sumtables
by epidata-list＠lists.umanitoba.ca 01 Jun '06

01 Jun '06

> Please discuss on the list if the /weight= x principle is what we > want. I have met various > needs for weighting, but assume that the simple frequency weight shown > here is sufficient. > > Regards > Hi everybody, I think there are two different situations where a WEIGTH variable should be necesary: The first situation is when working with data from epidemiologial surveillance. It is very usual that data sent to a upper level (for example National level from a regional level) are sent in an aggregated format. In order to be able to analyze this kind of data a command in the form of sumfreq disease /sum=COUNT (where COUNT is the weigth variable) is essential. The second situation is when working with data comming from a complex sampling design (Not a simple random-sample strategy). In this case it is necesary to specify not only the WEIGHT variable, but the STRATA and Primary Sampling Unit. The sintax for this situation could be something like: CFREQ VAR1 /W=WEIGHTVAR /S=STRATVAR /PSU=PSUVAR Greetings, Pedro Pedro Arias Bohigas John Ericssons gatan, 12 5 tr 112 22 Stockholm Sweden Phone (cell)+46(0)734421130

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Few suggestions about Epi Analysis
by epidata-list＠lists.umanitoba.ca 01 Jun '06

01 Jun '06

Dear Jens, Greetings. I hope Epi Analysis is making good progress. The graphic features are excellent addition.the Epi Ananlysis I tested old PGMs of Epi6 in Epi Analysis. Few more tweakings are further required. You know that long PGMs extendimg into pages are dealt fairly easily by Analysis.exe of Epi6.04. In Epi Analysis, when a particular set of "SELECT" commands do not select any records, the "program aborts the operation" and does not process rest of the commands of the PGM. "RECODE" command does not create e.g. age groups from age data. I strictly adopted the synytax of Epi Analysis. Analysis.exe (323 kb) of Epi info 6.04d could move mountains. It is not appropriate to compare Epi6.04 with Epi Analysis of 1.2. However Epi6 will always remain the inspiration. Long pending requirement of the portability of Epi info has been met by small sized Epidata, Epi-analysis and Flash memmory devices. Kindly keep the work going. Sincerely, Dr. Shavinder Singh

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[Fwd: RE: linux and Epidata]
by epidata-list＠lists.umanitoba.ca 01 Jun '06

01 Jun '06

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Sumfreq and Sumtables
by epidata-list＠lists.umanitoba.ca 01 Jun '06

01 Jun '06

1. Sumfreq / Sumtables (epidata-list(a)lists.umanitoba.ca) >Has anyone an idea on how to replace Sumfreq (or sumtables) with Epidata >analysis? >Thanks! >Gilles / Paris > > > > I understand the sumfreq and sumtables command to be able to do a frequency or crosstable but instead of counting observations the counting would be made with another variable. Example from testdata: read bromar tab agegrp . freq agegrp agegrp Age (10 year intervals) No. % 10 35 0.92 20 489 12.92 30 1198 31.64 40 1337 35.31 50 642 16.96 60 75 1.98 70 9 0.24 80 1 0.03 Total 3786 100% We can now collapse or aggregate the data file like this on agegrp: . agg agegrp /close //"agg" is the same as "aggregate" AGEGRP N 10 35 20 489 30 1198 40 1337 50 642 60 75 70 9 80 1 Now if we do a frequency on agegrp: agegrp Age (10 year intervals) No. % 10 1 12.50 20 1 12.50 30 1 12.50 40 1 12.50 50 1 12.50 60 1 12.50 70 1 12.50 80 1 12.50 Total 8 100% We have one observation for each value of agegrp. 8 records or observations in total. By listing all observations we can see that the variable N tells us how many are in each agegrp: list AGEGRP N 10 35 20 489 30 1198 40 1337 50 642 60 75 70 9 80 1 So in principle we would like a "backwards" aggregate where the weight or counting is by "N":: . freq agegrp /weight=n / Age (10 | year | intervals) | Freq. Percent ------------+-------------------- 10 | 35 0.92 20 | 489 12.92 30 | 1198 31.64 40 | 1337 35.31 50 | 642 16.96 60 | 75 1.98 70 | 9 0.24 80 | 1 0.03 ------------+------------------ Total | 3,786 100.00 Unfortunately the table just shown was made in Stata not in EpiData Analysis, but I have added sumfreq and sumtables to the workplan. Please discuss on the list if the /weight= x principle is what we want. I have met various needs for weighting, but assume that the simple frequency weight shown here is sufficient. Regards Jens Lauritsen EpiData Association

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