Public Administration Research Methods

Front 1

Statistics

Back 1

A set of techniques for the reduction of quantitative data to a small number of more convenient and easily communicated descriptive terms.

Front 2

Volume or qualtity measures

Back 2

-Measures of central tendancy
-Measures of variation

Front 3

Measures of central tendancy

Back 3

-Mean
-Median
-Mode

Front 4

Mean

Back 4

line x = sum times x divided by n

Front 5

Median

Back 5

The middle number is a dataset

Front 6

Mode

Back 6

The number that occurs most often

Front 7

Measures of variation

Back 7

-Range
-Others (won't use, but should know)
-The average deviation
-Variance

Front 8

Range

Back 8

The high minus the low

Front 9

The average deviation

Back 9

The mean absolute value of the distanced of each observation from the sample mean

Front 10

Variance

Back 10

The mean of the squared distances of each observation from teh sample mean

Front 11

Why n-1 for variance?

Back 11

Using n tends to produce an underestimate of the population variance, so we use (n-1) in the denominator to provide the appropriate correction for this tendency

Front 12

Why squared for variance?

Back 12

Positive and negative distances from the mean cancel each other out. We then take the square root, which balances it out.

Front 13

Standard deviation formula

Back 13

s = the square root of sum times x - line x squared divided by n - 1

Front 14

Standard deviation equation process

Back 14

-Start with subtracting the mean from individual observations. By doing this we find out how far each observation varies, or deviates from the mean.
-We square these deviations, to take care of the cancelling out of +/- distances
-The sigma (summation sign) says to add all the squared variations
-By then dividing the sum of the squared deviations by the number of observations, we get a mean squared deviation.
-Take the square root of the mean squared deviation, to get back to the original, intuitive units.

Front 15

What does standard deviation tell us?

Back 15

-Gives us some sort of indication of variability, so that one can compare two samples drawn from the same sort of units, and get some idea which varies more, which less.
-Measure of relative standing - things like percentile rankings
-It is a numerical measure of variability, just as a bell shaped frequency distrinution is a graphic representation of variability

Front 16

What does the distance tell us in standard deviation?

Back 16

How likely an observation from the mean is.