Statistics Chapter 3

Bimodal

A frequency distribution with two modes (two equal highest points). Often an indication that two separate and distinct groups lie within a population.

Bimodal distribution

Bimodal distribution that is symmetrical has the mean and median together in the center with the modes on each side.

Median

If the scores in a distribution are listed in order from smallest to largest, the median is the midpoint of the list.

Mode

In a frequency distribution, the mode is the score or category that has the greatest frequency.

Skewed distribution

In skewed distributions, the three values are in predictably different positions. In a positively skewed distribution, the order of the three from smallest to largest (left to right) is mode, median, then mean. Negatively skewed distributions are opposite.

Mean

The mean for a distribution is the sum of the scores divided by the number of scores.

Major Mode and Minor Mode

When two modes have unequal frequencies, the taller is often called the major mode and the shorter is the minor mode.

Multimodal

A distribution with several equally high points.

Central Tendency

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

Rectangular distribution

Rectangular Distribution has no mode because all x values occur at the same frequency. Mean and Median are in the center of the distribution.

Symmetrical Distribution

The right-hand side of the graph is a mirror image of the left-hand side. If it is perfectly symmetrical, the median is exactly at the center. The mean is also exactly at the center. If a distribution is roughly symmetrical, but not exact, the mean and median are close together in the center. For a perfectly symmetrical distribution with only one mode that is also in the center of the distribution, all three measures will have the same value. For a roughly symmetrical, they are clustered together in the center.