Changing Dictionary during Data Collection

[munirmdee1]

Hi all,

Is it possible to make some changes in the dictionary while the data collection has been started?

I'm asking because, I tried to change a dictionary and compile an application again and updated in tablets, but in some fields it showed *** instead of the data that has been collected when I tried to open in Modify mode.

I believed because Im using CSDB it wont be a problem, but I only changed the variable length size, from 3 digits to 4 digits, its a numeric field, and it failed to load some values in some other variables.

If its possible maybe there are somethings need to be considered or taken care before?

Thanks in advanced.

[josh]

There are certain dictionary changes that are ok to make once data collection has started and others that are not ok. Even when using csdb, CSPro uses the start position and length of items so anything change that moves the start position of an existing data item is going to cause problems like what you are seeing. In particular if you change the length of an item, the start positions of the rest of the items in the record changes. Similarly if you add or remove an item that is not at the end of the record, you change the start positions of the items that follow it. Here is what you can do without causing any problems with the existing data:

- Add a new item at the END of a record
- Add a new non required record

So if you need to add a new item, just put it at the end of the required. If you need to delete an item, just remove it from the form and leave it alone in the dictionary (it will just be blank in the data file for new questionnaires). If you need to change the length of an item your best option is to a add new item at the end of the record, remove the old item from the form (leave it in the dictionary) and replace it with the new item. Then for existing data use logic to copy from the old item to the new item.

In some scenarios you can use the reformat data tool to convert data from the old dictionary to the new dictionary. However this tool only works on Windows so if you want to change the dictionary on an interviewers Android tablet in the field it won't help.

[munirmdee1]

OK, thank you Josh.

Actually I reverted back to the first dictionary, and its working fine.

Thank you for your clarification.