Sometimes we see cells on a worksheet which are blank and sometimes we see cells which contain a null value. Does Sigma treat these equally?
A null value in Sigma represents the absence of a value.
A whitespace is not treated/counted or otherwise operated upon as a null value. Cells with whitespace do in fact contain a value, the whitespace.
Fortunately it is easy to convert whitespace values to null values in Sigma using Sigma Formulas.