MEASURES OF DISPERSION, LOCATION, RELATIVE POSITION Flashcards
Measures of Central Tendency
Mean
Median
Mode
This score is an extreme value in relation to other scores.
outlier
This central tendency is the most common one and is also called average. It is affected by outliers.
Mean
This central tendency is the middle score or the 50th percentile. It is unaffected by outliers and is preferred for ordinal scores or very skewed distribution.
Median
This central tendency represents the largest number of people. It is only used in nominal data.
Mode
This refers to how spread out the scores are.
Dispersion (variability)
This is a measure of dispersion which is the average of each score’s squared difference from the mean.
Variance
Population=Summation of (x-mean)^2 divided by N
Sample=Summation of (x-mean)^2 divided by n-1
Formula of standard deviation
Population= Square root of the [Summation of (x-mean)^2 divided by N] Sample= Square root of the [Summation of (x-mean)^2 divided by n-1]
This is a measure of dispersion is the difference between the highest value and lowest value.
Range
This is the ratio of standard deviation to the mean.
Coefficient of variation
Population= (std.dev/mean) x 100% Sample= (std.dev/mean) x 100%
This converts values to show where a given value stands in relation to other values of the same grouping.
Measures of Relative Position
100 equal parts
Percentile
10 equal parts
Decile
4 equal parts
Quartile
Refers to how well an individual did on the exam.
score
