Test on Statistical Analysis with SPSS: Core Methods

Question 1: When reporting the independent t-test results, it is typical to include the bootstrapped standard error for each group mean in the final summary.

A. Ano

B. Ne

Explanation: The study materials provide an example of reporting the independent t-test results, which includes the standard error (SE) for each group mean, but it specifies 'SE' as 0.48 and 0.55, which are the standard errors of the mean (Std. Error Mean) from Output 1, not the bootstrapped standard error estimates.

Question 2: According to the provided study materials, which of the following statements correctly describe the purpose or outcome of using bootstrapping in an independent t-test?

A. Bootstrapping helps reduce the impact of potential bias in the data.

B. Bootstrapping is used to re-estimate the standard error of the mean difference.

C. Bootstrapping is an alternative method to calculate the degrees of freedom for the t-statistic.

D. Bootstrapping is applied to generate confidence intervals for the difference between means.

Explanation: The study materials state that bootstrapping can reduce the impact of potential bias in the data and is used to generate confidence intervals for the difference between means. It also explicitly mentions that the bootstrapping procedure re-estimates the standard error of the mean difference. The materials do not indicate that bootstrapping is used to calculate degrees of freedom.

Question 3: Output 5, the Paired Samples Test table, reports the standard deviation of the differences between the means and the standard error of the differences between participants' scores in each condition.

A. Ano

B. Ne

Explanation: Output 5 shows the 'Paired Differences' section, which includes 'Std. Deviation' and 'Std. Error Mean' specifically for the difference between the two conditions. The study materials state, 'The table also reports the standard deviation of the differences between the means and more important the standard error of the differences between participants' scores in each condition.'

Question 4: The 95% confidence interval for the mean difference presented in Output 5 includes a value of zero.

A. Ano

B. Ne

Explanation: Output 5 shows the 95% confidence interval of the difference as ranging from -1.973 (lower limit) to -0.527 (upper limit). Both limits are negative, indicating that the interval does not contain zero.

Question 5: Based on Output 5 of the paired-samples t-test, which conclusion about the mean difference between 'Mischief (No Invisibility Cloak)' and 'Mischief (Invisibility Cloak)' is accurate?

A. The correlation coefficient between the two conditions is highly significant, r = .806.

B. The difference between the means was significant because the p-value (Sig. (2-tailed)) of .003 is less than .05.

C. The 95% confidence interval for the mean difference is -1.667 to -0.833, indicating no significant effect.

D. The degrees of freedom for the test statistic are 12, derived from the sample size of 12.

Explanation: Output 5 explicitly states, 'because the value of p is less than .05 we can conclude that there was a significant difference between the means of these two samples.' The Sig. (2-tailed) value in Output 5 is .003, which is less than .05, confirming a significant difference. Option 0 describes information from Output 4 (Paired Samples Correlations), not Output 5. Option 2 describes the bootstrap confidence interval from Output 6 and incorrectly interprets its significance. Option 3 incorrectly states the degrees of freedom; Output 5 shows df = 11, which is N - 1 (12 - 1).