Descriptive statistics

Measures of central tendency

an umbrella term for average manipulations

mean, median (middle val), mode

sample size

outliers

What happens if there isn't a true middle value

outliers

Numbers that are much greater or much less than the other numbers in the set

when is the median better

if there is outliers

measures of dispersion/variability

S^2

sample variance symbol

x bar represents

mean of a sample

n=

total data points

alpha variable

standard deviation

measured dispersion of the data

if n is large

s^2 is smaller

goal of variation

small variation

small sample size leads to

larger variation

range

the difference between the highest and lowest scores in a data set

interquartile range

The difference between the upper and lower quartiles.

(range between 1st and 3rd quarter)

percentile

Specific point in a distribution of data that has a given percentage of cases below it.

coefficient of variation

standard deviation/mean

variance equation

(sum of each sample point minus the mean)^2 / (Total # of counts)

standard deviation formula

the square root of the variance