If your data are already in SPSS, it will be simplest to use the same structure as you already have (probably one database).
If you are going to be gathering data and using EpiData to input new data, then you have a choice. I won't offer a real answer, except to say that the choice of one database or RELATED databases will depend on how you want to analyze the data and whether there are differences in data points at the three visits.
If the three visits have exactly the same variables, you can use two related databases: 1. demographics with case number as KEY 2. visits, using case number as KEY to allow you to related the files (there is an example for this in classic Epidata - household, person, visit at http://epidata.dk/examples.php) In Analysis, read the visits file first and then merge demographics based on case number
If the three visits have different data, then you could have four related databases: 1. demographics as before 2. visit 1 with case number as KEY 3. visit 2 4. visit 3 This arrangement makes it possible to do the data entry independently, but still bring all of the data together for analysis. In classic EpiData, people did this to keep the number of variables down in each of the files. However, the data are structured exactly like a single large database. In Analysis, ready any file first and merge based on case number
You can make a single database and still make it easy to enter data by having a variable VISIT and depending on the value (1,2,3) Jump to the first variable for that visit. In the new EpiData (Manager, EntryClient) you can do this quite easily.
Jamie
On 2013-04-01, at 6:17 PM, epidata-list@lists.umanitoba.ca wrote:
I'm changing my database from SPSS to EpiData. IIt's a follow-up database, with almost 1050 subjects, and three different time points (baseline, 1fst and 3rd months). In total, I have 703 variables. I wonder if you can help me with which choice should I take to collect and merge this kind of data? Is it better to create only one database (including all time points), or should I have to create three databases - one for each time point? If I create 3 databases, how can I merge it? Ex: case n. 999 - merge baseline data with 1fst month, and with the 3rd month... Can you inform where I can find exemples? T