Full Version: longitudinal, conditional data
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arodi
Hello Access gurus.

I am quite new to Access (but not to Excel or stats packages), and I hope I don't ask anything too basic here.

I am in the process of creating a large database of patient data. For each subject I plan to have around 30 variables. However, some of those variables might not always exist. For example, if subject A comes in for evaluation three times, I might have his/her weight at three time points. Meanwhile, subject B was only seen at the clinic twice. Of course, not only weight and date is recorded every visit, but around 10 variables.

A - Date1 - Weight W1
............- Height H2
..- Date2 - Weight W2
........... - Height H2
---------------------------------
B - Date 1 - Weight W1
............ - Height H2


What I have now is not optimal (Weight1, Weight 2, Weightn; Date1, Date2, Daten...). What would you recommend I do in the design of this database? I would like to create fields that exist 'only' if an evaluation was done. how could I do this?

Thank you all for your time and patience with the noobies.
Arodi
QDS
You could use a transaction table to record your data points and the title of each point.

For example, you would have a lookup table containing you data point titles such as "Weight", "BP", ect.

tlkpTitles

[*] TitleID
[*] Title

Then your next table would be used to store the title and the associated data, example:

tlbPatientdata

[*] PatientID
[*] EntryDate
[*] TitleID
[*] DataPoint

Very simple layout but saves a great deal of space in a large database

Richard
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