Which of the following relationships is NOT true in a model distribution?

In statistics, for a moderately skewed distribution, there exists a relation between mean, median, and mode. This mean median and mode relationship is known as the “empirical relationship”

• Mean is the average of the data set which is calculated by adding all the data values together and dividing it by the total number of data sets.
• Median is the middle value among the observed set of values and is calculated by arranging the values in ascending order or in descending order and then choosing the middle value.
• The mode is the number from a data set that has the highest frequency and is calculated by counting the number of times each data value occurs.

In the case of a moderately skewed distribution, i.e. in general, the difference between mean and mode is equal to three times the difference between the mean and median. Thus, the empirical relationship as Mean – Mode = 3 (Mean – Median). 

If solved further, Mode = 3 Median - 2 Mean and 3 Median = 2 Mean + Mode

Hence 2 Median - 3 Quartile Deviation = 2 Mean is NOT true in a model distribution.