If a data point has a corresponding z-score of -1.5 then it is one and a half standard deviations above the mean value.?

This statement is incorrect. A z-score of -1.5 indicates that the data point is one and a half standard deviations below the mean, not above it. In statistical terms, a negative z-score signifies that the value is less than the average of the dataset. Therefore, a z-score of -1.5 reflects a position to the left of the mean on the normal distribution curve.