Correlation and Association, continued. Standard units are a way of putting different kinds of observations on the same scale. The idea is to replace a datum by the number of standard deviations it is above the mean of the data. A datum that is above the mean by 2.5 times the SD is 2.5 in standard units. In fact, that is what it means for a set of data to be in standard units.
Standard units are dimensionless.
The difference between and the mean is which is SD s, so standard units. The difference between and the mean is which is SD s, so standard units. A weight of in standard units is average. The correlation coefficient r of two variables X and Y is the average of the product of X in standard units and Y in standard units . You must be sure to multiply the measurements corresponding to the same individual.