Dependent variable: Varies in a way that depends on something else
Descriptive statistics: Data about a set of data, like measures of central tendency and variability
Independent variable: Varies in a way that isn't dependent on something else
Interval scale: A measurement where distance between the measurements matter
Mean: The average of a set of numbers
Median: The middle value of a set of numbers
Nominal scale: A label, not really a measurement (has no quantitative value)
Non-parametric data: Data from ordinal or nominal scales
Ordinal scale: A measurement in rank order, distances between the measurements don't matter
Parametric data: Distributions are normal, interval or ratio data
Ratio scale: A measurement where absolute zero matters
| Test | Description | Variables |
|---|---|---|
| Single-sample t test | Compare the mean of your sample to a known mean | Dependent variable (the variable you are testing): ratio or interval |
| Paired-samples t test | Compares means of two scores from related samples |
Independent variable: one group Dependent variable: the same scale for both times measured, interval or ratio |
| Independent-samples t test | Compares the means of two groups for a single dependent variable |
Independent variable (the groups): two levels Dependent variable (the variable you are testing): ratio or interval |
| One-way ANOVA | Compares the means of groups that vary for a single independent variable |
Independent variable: can have many groups; must be independent Dependent variable: interval or ratio |
| Factorial ANOVA | Compares the means for multiple independent variables with multiple levels |
Independent variable: can have many groups with different levels, should be independent Dependent variable: interval or ratio |
| Repeated-Measures ANOVA | Compares means for related groups for more than one level of an independent variable | Dependent variable: measures should be from same or similar group, interval or ratio |