CH3-2300

Central Tendency

A statistical measure that defines a single score to represent the center of a distribution.

Mean

The sum of all the scores divided by the number of scores in the data.

Median

The midpoint of the scores in a distribution when they are listed in order from smallest to largest.

Mode

The score or category that has the greatest frequency in a frequency distribution.

Symmetrical Distribution

A distribution where the mean, median, and mode have the same value.

Skewed Distribution

A distribution where the mean is affected by extreme scores, and can be positively or negatively skewed.

Weighted Mean

A mean calculated by giving different weights to different scores.

Frequency Distribution

A summary of how often each different value occurs in a dataset.

Summation Notation

A mathematical notation used to represent the sum of a series of numbers.

Balance Point

The point at which the distribution would balance if plotted on a graph; associated with the mean.

Characteristics of the Mean

Changing a score usually changes the mean, and removing or adding a score can also affect it unless equal to the mean.

Real Limits

The range of values that a continuous variable can take, used to define the precise median.

Extreme Scores

Scores that are significantly higher or lower than the rest, which can skew the mean.

Discrete Variables

Variables that can take on a finite number of values.

Nominal Scale

A scale of measurement used for labeling variables without any quantitative value.

Ordinal Scale

A scale of measurement that deals with the order of values, but not the difference between them.