Which characteristic would NOT affect the calculation of a mean rent?

The characteristic that does not affect the calculation of a mean rent is the act of comparing median values instead. The mean is the average of a set of numbers and is calculated by summing all values and dividing by the total count. In contrast, the median is the middle value of a sorted list. Since comparing median values involves using a different measure of central tendency, it does not directly influence the calculation of the mean.

Each of the other options involves a direct alteration of the data considered for the mean calculation. Eliminating a data point can change the sum and count, thereby affecting the mean. Adding more data points also impacts both the sum and the count, with a potential effect on the mean value. Changing rent prices directly modifies the values being averaged, which will certainly change the mean rent figure. Thus, focusing on median values does not contribute to the mean calculation, making it the correct choice in this context.