This article is part of the Definitive Guide to Uploading and Preparing Data.
Merging datafiles may be necessary before you begin your official setup in Crunch. Of course, in tracking studies, merging data is important as well.
There are two types of data merging in Crunch: Appending and Joining.
- Appending datafiles adds more rows to create a larger dataset
- Joining datafiles is about merging in new variables
Append is what happens in a tracking study - you append the incoming wave of data to the existing dataset.
An example of an append in the initial upload phase, is where you may have different datafiles that belong to the same study, but you need to bring them together. For example, you may have different data files pertaining to different countries (one data file for each country). You would need then append each country in succession to make one large dataset.
In the web app
- You upload each dataset separately, and then append each dataset in succession (eg: Dataset B is appended to Dataset A to make dataset A larger. Dataset B can then be discarded. Dataset C can then be appended to dataset A to make it even larger, and so on.
- See the functions under Multiple Datasets in the crunch R package documentation.
- Also read this vignette: Fork and Merge