Stats Flashcards
IV
manipulated by researcher, presumed to be the agent of change
DV
measured by researcher to determine if IV has an effect
Quasi-independent variable
IV in quasi-experiemtne (using existing groups rather than random assignment in determining condition)
Variance
Sum of squared deviations from the mean, divided by N-1. Less susceptible to extreme values/outliers
Standard deviation
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.
Eta-squared
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
Beta weight
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
Correlation: r-squared
Proportion of variation in one variable accounted for by the linear relationship with another
p value
The level of significance, or the probability that the null hypothesis is false
Kappa Coefficient
Used to evaluate inter-rater reliability
Coefficient Alpha
Stats used to assess the internal consistency reliability
Pearson’s r
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
Pooled variance
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
Moderator variable
A variable that affects the magnitude of direction of the relationship between the independent variable and the dependent variable
Mediating 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)
Outcome variable
The dependent variable for a prediction in an experiment; it should be clinically relevant
Suppressor variable
Lowers or covers the relationship between variables
Criterion contamination
Occurs when the operational or actual criterion includes variance that is unrelated to the ultimate criterion.
Chi-Square test
Examines frequency distribution of categorical variables such as political party affiliation or eye color. Non-parametirc, does not require normality.
Goodness-of-fit
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.
T-test
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
One-sample t-test
Tests they hypothesis that a single sample mean is different than a specific hypothesized value
Independent-samples t-test
Test the hypothesis that two unrelated samples are different from each other
Related or dependent-samples t-test
Tests the hypothesis that the difference between two related samples (pre/post scores, scores of siblings) is not equal to 0 (samples have different means)
Main effect
Arising from ANOVA terminology; represents the effect of an independent variable on Y averaged across the (main or interaction) effects of other independent variables.
Interaction
The circumstance in whciht the impact of one variable on y is conditional on (varies across) the values of another predictor
Kolmogorov
An uncommon stat that utilizes ordinal or ranking data.
Power
The probability of rejecting a null hypothesis that is false
ANOVA post-hoc tests
If a significant difference exists, a post-hoc test will be a more focused examination of which means differ from which. Scheffe (conservative) Tukey’s HD, Fisher’s LSD (liberal)
Factorial or n-way ANOVA
n represents the number of IVs or factors. Used when examining the effects of two or more IVs.
Mixed-design ANOVA
Multiple IVs including both within-subjects (time) and between-subjects (condition) factors. Ex. pre/post test with control condition.
Kruskal-Wallis
An alternative test to the one-way ANOVA that can be used to compare two or more independent groups
Randomized Block ANOVA
A statistical test that controls for the effects of extraneous variables by grouping (“blocking”) the subjects based on the variable and then assigning each subject to one of the interventions; the confounding variable is therefore handled as if it were an independent variable.
Cluster sampling
Sampling technique involving naturally occurring groups (clusters)
Stratified sampling
Sample drawn from each stratum; main objective is improved precision
Multistage sampling
More complex form of cluster sampling. Population divided into start at highest level, then sample s drawn and stratified at lower level; procedure repeated until at lowest hierarchical level
Systematic sampling
A simple, random sampling of each stratum of the population. Additional variables may also be stratified, such as gender.
Random selection
Drawing a sample from a population in such a way that each member has an equal probability of being selected
Experimental Design
Researc in whcih random assignment is used to place subjects in groups that will receive different aspects of the variable in question.
Proband
AKA patient zero; the first family member to seek professional attention for a disorder
Normal distribution
mode = median = mean