AP Psychology - Module 1, Lesson 4

Measures of Tendency and Variation and Ethics

Inferential Statistics

Statistics that use data to make references and conclusions about whether a hypothesis was supported by results.

Positively Skewed Data

When the mean is usually greater than the median, which is always greater than the mode.

Negatively Skewed Data

In a graph, when the mean is usually less than the median.

Statistical Significance

A statistical statement of how likely it is that an obtained result occurred by chance.

P-Value

A calculated formula to determine the likelihood that the obtained result will occur again.

Descriptive Statistic

Statistics that use quantitative data to describe behavior.

Z Score or Standard Score

The number of standard deviations from the mean a data point is. Tells you how far away a data point is from the average.

Standard Deviation

A way to figure out how much each individual score varies from the mean.

Measures of Variation

Are used to describe the distribution of the data. Includes range and standard deviation.

Measures of Central Tendency

Statistical methods used to determine the center of a researcher's data; mean, median, and mode.

Mean

The numerical average of a set of scores.

Median

The middle score in a set of scores.

Mode

The most frequently occurring score in a set of scores.

Normal Curve

A symmetrical, bell shaped distribution of data where most scores cluster around the mean, with fewer scores falling at either extreme end.

Percentile Rank

The percentage of individuals in a given population who scored at or below a specific score on a test.

Range

The difference between the highest and lowest scores in a set of scores.

Regression Toward the Mean

The tendency for extreme and unusual scores to fall back toward the average.

Variation

Refers to how spread apart the scores of a set of scores are or how much the scores vary from each other.

Central Tendency

Are examples of descriptive data statistics that depict an overall "central" trend of a set of data.