Statistical Concepts Quiz

You perform a paired-samples t-test on pre-test and post-test scores. The results are: t(29) = 3.11, p = .004. What conclusion can you draw?

• There is a significant difference between pre-test and post-test scores.

• The null hypothesis cannot be rejected.

• Pre-test scores are significantly higher than post-test scores.

• The test is invalid because p < .01.

Which of the following represents the null hypothesis in a two-sample t-test?

• The means of the two samples are different.

• The variances of the two samples are equal.

• The means of the two samples are equal.

• The distributions of the two samples are identical.

If you perform a t-test and obtain t(20) = 0.52, p = .608, what can you conclude?

• The null hypothesis is rejected.

• There is no significant difference between the group means.

• The test suggests the alternative hypothesis is true.

• The test is invalid because the t-value is too small.

An experiment has three groups with the following means: Group 1 = 10, Group 2 = 15, Group 3 = 12. The ANOVA result is F(2, 27) = 3.29, p = .048. What does this tell us?

• There is no significant difference between the groups.

• At least one group mean is significantly different from the others.

• Group 2 is significantly different from Group 1.

• The variances of the groups are unequal.

What is a key limitation of ANOVA as an omnibus test?

• It cannot detect significance between groups.

• It cannot identify which specific group means differ.

• It requires equal sample sizes across groups.

• It assumes non-parametric data.

Which assumption is specific to repeated-measures ANOVA?

• Normality.

• Homogeneity of variance.

• Sphericity.

• Independence of observations.

An ANOVA is conducted, and the post-hoc tests show significant differences for Group 1 vs. Group 2 (p = .01) and Group 1 vs. Group 3 (p = .03). What can you conclude?

• Group 1 differs significantly from Groups 2 and 3.

• Groups 2 and 3 differ significantly.

• All group means are significantly different.

• The ANOVA is invalid without equal group variances.

Which of the following best describes the purpose of regression analysis?

• Testing whether two means differ.

• Determining whether a dependent variable predicts an independent variable.

• Modeling the relationship between predictors and a dependent variable.

• Calculating the variance of a single variable.

In a regression analysis, the intercept of y=3x+5 represents:

• The increase in yy for a 1-unit increase in x.

• The predicted value of y when x=0.

• The slope of the regression line.

• The error in the model.

If a Pearson correlation produces r=−0.72, what does this mean?

• There is no relationship between the two variables.

• There is a strong negative linear relationship.

• The variables are positively correlated.

• The correlation coefficient is not significant.