Page 164 - DMGT404 RESEARCH_METHODOLOGY

Research Methodology

Notes Indicates the degrees of the scatteredness of the observations. Let curves A and B represent two
frequency distributions. Observe that A and B have the same mean. But curve A has less variability
than B.
If we measure only the mean of these two distributions, we will miss an important difference
between A and B. To increase our understanding of the pattern of the data, we must also measure
its dispersion.
Let us understand various measures of dispersion:
1. Range: It is the difference between the highest and lowest observed values.

i.e. range = H – L, H = Highest, L = Lowest.

Notes

1. Range is the crudest measure of dispersion.
H – L
2. is called the coefficient of range.
H + L

2. Semi-inter Quartile Range (Quartile deviation): Semi-inter quartile range Q.

Q – Q
Q is given by Q = 3 1
2

Notes

Q – Q
1. 3 1 is called the coefficient of quartile deviation.
Q  Q 1
3
2. Quartile deviation is not a true measure of dispersion but only a distance of scale.

3. Mean Deviation (MD): If A is any average then mean deviation about A is given by:
 f |x – A|
MD(A) = i i
N

Notes

f  |x  x |
1. Mean deviation about mean MD(x)= i i
N
2. Of all the mean deviations taken about different averages mean derivation about
the median is the least.

MD(A)
3. is called the coefficient of mean deviation.
A

158 LOVELY PROFESSIONAL UNIVERSITY