**Merits of Arithmetic mean**

- It has a specific formula.
- It is easy to calculate and understand.
- It uses all the observations in the data set.
- Further algebraic treatment is possible on the mean and hence further analysis can be carried out.
- It is not affected much by sampling fluctuations. Sampling fluctuations are the variation in the statistic value for different samples from the same population.

**Demerits of Arithmetic mean**

- It is affected by extreme values. Note here that the median and mode are not easily affected by extreme values. As an example, consider the following data sets and their central tendencies.
*
**In the above table, the value 500 creates a huge difference in the mean but brings no change in the mode and median**.

- It is a value which may not be present in the data
- Sometimes it gives absurd results for example while calculating the average number of books in the library per subject, the mean could be 250.32 books.
- If data contains open end class intervals than it cannot be calculated
- Since the mean is based on all observations, even if one observation is missing, we cannot calculate the mean.
- It can’t be found graphically.

MODE

MEDIAN

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