t-tests
What is the difference between independent and dependent t-tests?
Independent t-tests compare means from two different groups, while dependent t-tests compare means from the same group at two points in time.
What does the f-statistic represent in ANOVA?
The ratio between group variance to within group variance.
What does the slope represent in a regression equation?
The range in the dependent variable for every one-unit increase in the IV.
What is Cohen’s d used for?
Measuring the effect size or magnitude of difference between two group means.
What is a null hypothesis?
A statement that there is no effect or no difference.
What is the formula for degrees of freedom in an independent t-test?
df = n1-n2-2
What type of question does one-way ANOVA address?
Whether the means of three or more groups differ significantly
What is the formula for the regression line?
Y-hat = b0 + b1X1
What is a small effect size for Cohen’s d?
0.2
What is a directional hypothesis?
A hypothesis that specifies the direction of the expected effect (e.g., μ1>μ2 ).
What is the null hypothesis for an independent t-test?
The means of the two groups are equal (mu1 = mu2)
What is the purpose of a post-hoc test in ANOVA?
To determine which specific groups differ after a significant f-statistic.
What is R2 in regression?
The proportion of variance in the dependent variable explained by the independent variable(s).
Why is effect size important even when pp-values are significant?
It provides information about the practical significance of the findings.
Why is it important to specify a null and alternative hypothesis in statistics?
To provide a framework for testing and interpreting results.
How do you determine the critical value of t?
Use the t-distribution based on the df and the significance level.
What is the formula for the f-statitic in a One-Way ANOVA?
F = MSbetween/MSwithin
What assumption must be met regarding residuals in regression?
Residuals must be normally distributed with constant variance (homoscedasticity).
How is effect size calculated for an ANOVA?
eta2 = SSbetween/SStotal
What happens if the p-value is greater than α?
Fail to reject the null hypothesis.
What is the S2p in the context of t-tests?
It is the pooled variance, calculated as a weighted average of variances from two groups.
In ANOVA, what does the MS stand for?
Mean square, which is calculated as SS/df
What does the standard error of estimate measure?
The average distance between observed and predicted values.
What distinguishes Cohen’s d from eta2?
Cohen’s d is used for mean differences, while η2η2 measures variance explained in ANOVA.
What is the difference between a one-tailed and a two-tailed test?
A one-tailed test predicts a specific direction of the effect, while a two-tailed test looks for an effect in either direction.