8/3/2019 Stats Outline
1/2
4.2 Arithmetic Mean
This is the most commonly used average which you have also
studied and used in lower grades.Here are two definitions given by
two great masters of statistics.
Horace Sacrist : Arithmetic mean is the amount secured by
dividing the sum of values of theitems in a series by their
number.
W.I. King : The arithmetic average may be defined as the sum of
aggregate of a series of itemsdivided by their number.
4.4 Median
It is the value of the size of the central item of the arranged
data (data arranged in the ascendingor the descending order). Thus,
it is the value of the middle item and divides the series in to
equalparts.
4.5 Mode
It is the size of that item which possesses the maximum
frequency. According to Professor
Kenney and Keeping, the value of the variable which occurs most
frequently in a distribution iscalled the mode.
5.3 Range
In any statistical series, the difference between the largest
and the smallest values is called asthe range.
5.4 Mean Deviation
Average deviations ( mean deviation ) is the average amount of
variations (scatter) of the items ina distribution from either the
mean or the median or the mode, ignoring the signs of
thesedeviations by Clark and Senkade.
5.5 Variance
The term variance was used to describe the square of the
standard deviation R.A. Fisher in 1913.
Standard Deviation (s. d.)
It is the square root of the arithmetic mean of the square
deviations of various values from theirarithmetic mean. it is
denoted by s.d. or s.
5.7 Percentile
The nth percentile is that value ( or size ) such that n% of
values of the whole data lies below it.
For example, a score of 7% from the topmost score would be 93
the percentile as it is above 93%of the other scores.
5.8 Quartiles And Interquartile Range
If we concentrate on two extreme values ( as in the case of
range ), we dont get any idea aboutthe scatter of the data within
the range ( i.e. the two extreme values ). If we discard these
twovalues the limited range thus available might be more
informative. For this reason the concept ofinterquartile range is
developed. It is the range which includes middle 50% of the
distribution.Here 1/4 ( one quarter of the lower end and 1/4 ( one
quarter ) of the upper end of the
