Quiz with Formula Questions Removed

What does the independent t-test compare?

• Medians of two samples from known populations

• Standard deviations of two samples

• Variances of two samples

• Means of two samples from unknown populations

Answer explanation

The independent t-test compares the means of two samples from unknown populations to determine if there is a statistically significant difference between them, making the correct choice the means of two samples from unknown populations.

The percentage of variance accounted for (r2) measures:

• The difference between means

• The standard error of the mean

• The correlation coefficient

• The effect size or change on the dependent variable due to the independent variable

Answer explanation

The percentage of variance accounted for (r2) indicates how much of the variability in the dependent variable can be explained by the independent variable, thus measuring the effect size or change.

What is sp2 in the independent t-test formula?

• Sample variance

• Population variance

• Estimated standard error

• Pooled variance

Answer explanation

In the independent t-test formula, sp2 represents the sample variance, which is used to estimate the variability within each sample. This is crucial for calculating the t-statistic and determining the significance of the test.

In a _ design, each participant is measured only in one condition.

• independent

• repeated measures

• within-subjects

• crossover

Answer explanation

In an independent design, each participant is assigned to only one condition, ensuring that their responses are not influenced by other conditions. This contrasts with repeated measures and within-subjects designs, where participants experience multiple conditions.

A difference score is calculated by:

• Adding the first and second scores

• Multiplying the first and second scores

• Averaging the first and second scores

• Subtracting the first score from the participant's second score

Answer explanation

A difference score is determined by subtracting the first score from the second score. This method highlights the change or difference between the two scores, making it the correct choice.

In a matched-subjects design, participants in two groups are:

• Measured twice

• Measured in every condition

• Measured only once

• Matched on the variable being measured

Answer explanation

In a matched-subjects design, each participant is only measured once, allowing for direct comparisons between the two groups without repeated measures. This distinguishes it from designs where participants are measured multiple times.

Which test uses mean difference scores to test for differences in data?

• Independent t-test

• One-sample t-test

• z-test

• Paired-samples t-test

Answer explanation

The paired-samples t-test uses mean difference scores to compare two related groups, assessing whether their means differ significantly. This distinguishes it from the independent t-test and one-sample t-test, which do not use mean differences.

Which of the following is NOT another name for a paired-samples t-test?

Answer explanation

The correct choice is 'independent t-test', as it refers to a different statistical test used for comparing means of two independent groups, unlike the paired-samples t-test which compares means from the same group at different times.

What is different about the means in the numerator of the repeated measure compared to the other two t-tests?

• The repeated measure uses the sample means.

• The repeated measure uses the population means.

• The repeated measure uses the sum of the means.

• The repeated measure uses the difference of the means.

Answer explanation

The repeated measure t-test uses sample means to compare differences within the same subjects across conditions, unlike independent t-tests that compare means from different groups.

What aspect does the repeated measure test decrease when compared to an independent t-test?

• Mean differences

• Sample size

• Degrees of freedom

• Variability

Answer explanation

The repeated measures test decreases degrees of freedom compared to an independent t-test because it uses the same subjects across conditions, leading to fewer independent pieces of information in the analysis.