Regression Analysis

Hypothesis

A proposed explanation for a fairly narrow phenomenon or set of observations.

Theory

A set of principles that is well substantiated by repeated testing and explains a broad phenomenon.

Independent Variable

Variables that do not depend on any other variables.

Dependent Variable

Variables that depend on independent variables.

Nominal Scale

A scale where data can be categorized into different, unrankable groups.

Ordinal Scale

A scale where data can be categorized into different, rankable groups.

Interval Scale

A scale with rankable values in which value differences are meaningful, but not value ratios.

Ratio Scale

A scale with rankable values where both value differences and value ratios are meaningful.

Validity

An investigation of whether the question we are asking actually measures what we wish to measure.

Reliability

An investigation of whether the measurement is free from errors.

Population

The whole group we wish to investigate.

Sample

A subset of the population, ideally chosen at random.

Graphical Methods

Methods used after collecting data to summarize it; includes pie charts, bar charts, and box plots.

Mean

The average value in a data set.

Median

The middle value of a data set when organized in order.

Mode

The value that occurs most frequently in a data set.

Variance

A statistical measurement of the spread between numbers in a data set.

Standard Deviation

A measure of how dispersed the data is in relation to the mean.

Normal Distribution

A continuous probability distribution where values lie in a symmetrical fashion around the mean.

Standard Normal Distribution

A normal distribution with a mean of zero and standard deviation of one.