Hi Statalist!

I would really need your help on this before-christmas issue!

I'm constructing an index made by the sum of three variables, which all vary in the range [0,1] (as they have been divided by their theoretical maximum).

Depending on the sample analyzed, it is not always assured that the three variables have the same variances (and st. deviations). In order to attribute them the same importance, one solution, before making the sum, would be to standardize them (subtracting the mean and dividing by the standard deviation). In this case the index would correspond to the sum of standardized scores.

My questions are:

- is standardization necessarily required? would it have other drawbacks (apart from changing the scale)?

- would you reccommend standardization or another solution?

- Could the sum of unstandardized scores be OK?

Thanks a lot and happy XMAS!

I would really need your help on this before-christmas issue!

I'm constructing an index made by the sum of three variables, which all vary in the range [0,1] (as they have been divided by their theoretical maximum).

Depending on the sample analyzed, it is not always assured that the three variables have the same variances (and st. deviations). In order to attribute them the same importance, one solution, before making the sum, would be to standardize them (subtracting the mean and dividing by the standard deviation). In this case the index would correspond to the sum of standardized scores.

My questions are:

- is standardization necessarily required? would it have other drawbacks (apart from changing the scale)?

- would you reccommend standardization or another solution?

- Could the sum of unstandardized scores be OK?

Thanks a lot and happy XMAS!

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