I have two data sets A and B. Set A has 6000 cases but has interested variable V1. Set B has a variable V2. The cases are generic in set B (so cannot merge with Set A by case).
I want to add V2 from Set B to Set A, by matching with the V1 variable, not by cases. Is there a way to do it?
Thank you for your time. I appreciate for the help.
Venu
Hello Venu,
Unfortunately, it's not clear in your query as to why you'd like to do this. Perhaps if you were to elaborate on your specific research question/aim (and explain the data/variables a little more), then someone could offer more constructive advice.
In general, the moment you match scores on different variables from different cases to each other, you introduce a relationship between your target variables (V1 and V2) that is almost guaranteed to differ from what exists in the population. Matching based on variable values is likely to bias that relationship even more sharply.
Good luck with your work.
Without a unique identifier in both datasets it's tricky to merge. But if you know the participants are the same in both datasets and you have a set of variables in both datasets you can reasonably expect to be identical, you might be able to match cases. For example: age, gender, ethnicity, & height. Compute a new variable (participant number) as the product of primes raised to the power of each respective variable in common. For example: 2^age * 3^gender * 5^ethnicity * 7^height. If necessary, first assign numbers to values of variables and be sure to use the same primes matching the same variables with the same values in both datasets. By the Fundamental Theorem of Arithmetic, each unique combination of your matching variables has a unique computed "participant number." If you have two or more identical participant numbers in the same dataset, unfortunately you'll need to exclude those when merging datasets (hopefully few). Now you can match by case. Hope this helps some, Venu! ~ Kevin
Thank you kevin and David appreciate for the recommendations. Looks like there no better way to do it. I ended up physically recoding the variables.
I will be more specific with my question next time. Appreciate for your time!
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