Dispersion Flashcards
Range
Coefficient of Range
L-S
L-S/L+S x 100
Range of Y
|b| x Range of x
MD of A
1/n E |x-A|
MD of A
1/n E |x-A|f
Coefficient of MD
Mean Deviation about A / A x 100
MD of y
|b| x MD of x
MD about median
E |X -median| / n
Coefficient of Mean deviation
MD about median / median x 100
S.D discrete
square root (E(xi - /x)2 /n )
S.D Grouped Frequency
square root (Ef (xi - /x)2 /n )
Variance = s^2
square root (E(xi - /x)2 /n ) [Unclassified data]
square root (Ef (xi - /x)2 /n ) [grouped frequency]
Coefficient of Variation (CV)
SD/AM x 100
SD of first n natural numbers is SD
Square root ( n^2 -1) / 12
If all the variable of X is k is equal
SD = 0
Standard Deviation remains unaffected due
to Change of origin but it is affected in the same ratio due to a change in scale.
Sy = |b| Sx
Combined SD
Square root (n1s1^2 + n2s2^2 + n1d1^2 + n2d2^2) / n1+n2
QD
Q3 - Q1/2
Coefficient of QD
Q3 - Q1 / Q3+Q1 x 100
Absolute measure of deviation
Range
SD
Mean Deviation
Quartile deviation
Relative Measure of Deviation
Coefficient of Range
Coefficient of Variation
Coefficient of mean deviation
Coefficient of Quartile deviation
For comparing two or more distributions,
Relative measure are considered and not absolute measure are considered
Why Range is not regarded as Ideal measure of Dispersion ?
Since it is based on only two observations
