The number of malaria cases reported during the last 10 years in a town is given below, 250, 320, 190, 300, 5000, 100, 260, 350, 320, and 160. The epidemiologist wants to fmd out the average number of malaria cases reported in that town during the last 10 years. The most appropriate measure of average for this data will be-
Measures of central tendency (statistical average) are -


Mean (arithmetic mean)
Median
Mode


In the given set of values of incidence of malaria one value (i.e. 5000) is an extreme score .
This extreme score will highly effect the mean. Mean is very sensitive to extreme scores. Mean in this case would be = 960 which does not at all represent the average incidence of malaria in the area.
Median is insensitive to extreme scores in a distribution. The median would not be effected by the extreme value of 5000. Median in this case is 300 which is nearer to the truth and therefore is a better representative of the incidence of malaria in past 7 yrs.
Mode is also not affected by the extreme values in the observation but it is difficult to calculate therefore not used to express the averages.
In distribution with extreme values -


Most affected measure of central tendency → mean
Least affected measure of central tendency → mode
Most preferable measure of central tendency → median
Arithmetic mean
Mode
Median
Geometric mean