Why wasn't n-1 used in the denominator for this sample calculation?

CFA Level I Quant
#1

I know that n-1 should be used when using sample data, but how do we know when to use n-1 or n because it seems to vary

For example, question asks to calculate the mean absolute deviation for a sample

I calculated it using n-1 in the denominator because it was using sample data and it should’ve been just n.

For calculating MAD, is n-1 never used even for sample data?

#2

You use n – 1 for calculating sample variances (and, thus, standard deviations); you use n for calculating sample means.

I’ve never heard of using n – 1 for calculating sample MADs, but I think that you should, for the same reason as for calculating sample standard deviations. Apparently the world doesn’t agree with me. It ain’t the first time.

#3

Ok so only calculations for variances or standard deviations should use n-1 if based on sample data

MAD should too, but I will just remember to calculate this using n

#4

For MAD you should use n. For other calculations you can use n-1 .

#5

The question wasn’t whether; the question was _ why _.