Final answer:
The limitation of covariance is that it does not indicate the strength of the relationship between variables unless they are in the same units and it is prone to scaling issues.
Step-by-step explanation:
The limitation of covariance as a descriptive measure of association is that it does not indicate the strength of the relationship between two variables unless they are measured in the same units. Covariance can display either a positive relationship or a negative relationship, but this alone is not adequate to determine the strength of the association. Covariance is also prone to scaling issues, meaning that the value of covariance can be misleading if the units of measurement for the variables differ.
For instance, a high covariance value doesn't necessarily mean a strong relationship, as it could be due to the scale of the measurements. Instead, the correlation coefficient r, which has been standardized, provides both the direction and the strength of a linear relationship between two variables on a scale from -1 to 1.