statistics

Central tendency

Used to summarize data and give one score that seems

typical of your sample

Mode

the most frequently occurring score(s) in a distribution

Mean

the arithmetic average of a distribution, obtained by adding

the scores and then dividing by the number of scores

Median

The middle score in a distribution: half the scores are above,

and half the scores are below

Variability

the spread or dispersion of scores in a data set, indicating how much individual observations differ from one another and from the mean

Range

the difference between the highest and lowest scores

Normal curve

A symmetrical

bell-shaped curve that

describes the

distribution of many

types of data; most

scores fall near the

mean and fewer and

fewer near the

extremes (outliers)

Standard deviation

a computed measure of how much scores vary around the mean score

Statistical significance

a statistical statement of how likely it is that an

obtained result occurred by chance.

Bar graph

Histogram

Polygon

Line graph

Positive skew

a distribution where the data tail extends to the right, indicating a concentration of scores on the left and a few high, extreme scores on the right

Negative skew

a data distribution where most scores are high, resulting in a long "tail" of lower scores extending to the left on a graph, making the mean less than the median

Inferential statistics

numerical data that allow one to generalize– to infer

from sample data the probability of something being true of a

population

Reliability

the consistency and repeatability of a measurement tool, such as a psychological test