manipulated by researcher, presumed to be the agent of change
measured by researcher to determine if IV has an effect
IV in quasi-experiemnt
(using existing groups rather than random assignment in determining condition)
Sum of squared deviations from the mean, divided by N-1. Less susceptible to extreme values/outliers
Square root of the variance
r-squared (single predictor), R-squared (multiple predictors)
Proportion of variation accounted for in one variable through linear relationship with another (or others). Not good for sample-to-sample comparisons. Reflects a reduction in error.
Proportion of variance accounted for in one variable thru relationship (not necessarily linear) with another (or others)
Squared factor loading
Proportion of variance accounted for in one variable by a factor
Standard regression coefficient
Coeffeicient of Nondetermination
One minus r-squared; proportion of variation in the dependent variable not associated with independent variables
Chi-square: Cramer's phi
Strength of relationship between two variables in a contingency table
t-test: Cohen's d
Difference between two group means in terms of a standard deviation (control group or pooled)
ANOVA: eta-squared, omega-squared
Proportion of variation in the DV accounted for by the IV
Proportion of variation in one variable accounted for by the linear relationship with another
The level of significance, or the probability that the null hypothesis is false
Used to evaluate inter-rater reliability
Stats used to assess the internal consistency reliability
A correlation stat used primarily for two sets of data that are of the ratio or interval scale; it is the most commonly used correlational technique
The weighted average of two sample variances. Provides better estimate of population variance than either sample alone.
Mean Squared Within (MSW)
A measure of error variation used in ANOVA
A variable that affects the magnitude of direction of the relationship between the independent variable and the dependent variable
A variable explaining the process by which the IV affects the DV (therapy affects depression by creating a more positive self-image, which then lessens depression)
The dependent variable for a prediction in an experiment; it should be clinically relevant
Lowers or covers the relationship between variables
Occurs when the operational or actual criterion includes variance that is unrelated to the ultimate criterion.
Examines frequency distribution of categorical variables such as political party affiliation or eye color. Non-parametirc, does not require normality.
One-way Chi-Square test for examining frequency distribution of one IV. May use expected frequencies (like expected percentage)
Test for independence
Two-way Chi-Square test for examining contingency table for 2 variables to determine wether they are independent (un-related). Requires counts, not percentages and requires a count of at least 5.
An inferential statistical procedure used to test whether the means of two groups are equal to each other.
The t-test is more powerful (more likely to reject the null hypothesis) when:
Larger sample size(s); larger mean difference; smaller sample variation