Predictor variable and Variable quantity

Predictor variable noun - A variable that can be used to predict the value of another variable (as in statistical regression).

Variable quantity and predictor variable are semantically related. In some cases you can use "Variable quantity" instead a noun phrase "Predictor variable".

Variable quantity noun - A quantity that can assume any of a set of values.

Predictor variable and variable quantity are semantically related. Sometimes you can replace phrase "Predictor variable" with "Variable quantity", this phrases are similar.