Measures of Variability

Measures of variability

is used for describing the spread data or variation around a central value

Range

the difference between the highest and lowest sample values

range

weakest/simplest measure of variability

Variance

average of squared deviation values from the distribution mean

Square of SD

standard deviation

measures the spread or dispersion of each value from the mean of distribution

Sqaured root of the value of the variance

standard deviation

most reliables measure of variability

Average of the distribution

Measures of Position

used to locate the relative position of a data value in the data set

can be ised to compare data from diff. /within the same data set

measures of position

inclides z scores and fractiles

Z scores

tells how many SD a data value is above or below the meam for a specific distribution of values

Z scores

Is obtained by subtracting the mean from the given value amd dividing the result bu the SD

Fractiles

are measures of location which include central location and any position based on the no. of equal divisions in a ny given distribution

Quartiles

it divide a distribution into 4 equal parts

Deciles

Same concept as percentiles excepts it divides sets into 10

Percentiles

Position measures used in in educational and health-related fields to indicate the position of an individuals in a group

Percentiles

Divides data set in 100 equal groups

Percentiles

it indicates the percentage of ddata values that fall below the specified rank

Measures of Variability

enables the researchers know how varied observations. Whether they are extreme values in distribution or very closw to each other

Measures of Variability

If the measure of variation is zero it means there is no variation and the observations are homogeneous.