Midterm Practice Answer Key PDF

**Practice Questions** 1. Which of the following is NOT a form of descriptive statistics?\ a) Mean\ b) Median\ c) t-test\ d) Mode 2. What does a 95% confidence interval represent?\ a) The interval within which the population mean definitely lies\ b) The interval in which...

**Practice Questions** 1. Which of the following is NOT a form of descriptive statistics?\ a) Mean\ b) Median\ c) t-test\ d) Mode 2. What does a 95% confidence interval represent?\ a) The interval within which the population mean definitely lies\ b) The interval in which we are 95% confident the sample mean lies\ c) The range where 95% of the data points fall\ d) The range in which we are 95% confident the population mean lies 3. What is the primary purpose of inferential statistics?\ a) To describe data\ b) To make predictions about a population based on a sample\ c) To calculate sample means\ d) To determine outliers in a dataset 4. If you increase the sample size (N), what happens to the confidence interval (CI)?\ a) It gets wider\ b) It gets narrower\ c) It stays the same\ d) It gets longer 5. Which of the following best defines the standard error of the mean (SEM)?\ a) The standard deviation of the sampling distribution of the sample mean\ b) The standard deviation of the population\ c) The standard deviation of the sample\ d) The difference between the sample mean and population mean 6. The p-value in hypothesis testing represents:\ a) The probability that the null hypothesis is true\ b) The probability of obtaining a result as extreme as the observed, assuming the null hypothesis is true\ c) The probability of making a Type I error\ d) The probability of making a Type II error 7. If p \<.05 in a statistical test, we:\ a) Fail to reject the null hypothesis\ b) Reject the null hypothesis\ c) Accept the null hypothesis\ d) Accept the alternative hypothesis 8. A Type I error occurs when:\ a) The null hypothesis is incorrectly rejected\ b) The null hypothesis is incorrectly accepted\ c) The alternative hypothesis is incorrectly accepted\ d) The alternative hypothesis is incorrectly rejected 9. A Type II error occurs when:\ a) The null hypothesis is incorrectly rejected\ b) The null hypothesis is incorrectly accepted\ c) The alternative hypothesis is incorrectly rejected\ d) The alternative hypothesis is incorrectly accepted 10. Power in statistical testing refers to:\ a) The probability of rejecting a true null hypothesis\ b) The probability of accepting a false null hypothesis\ c) The probability of correctly rejecting a false null hypothesis\ d) The probability of committing a Type I error 11. What is the effect of increasing the sample size (N) on the power of a test?\ a) It increases power\ b) It decreases power\ c) It has no effect on power\ d) It increases the likelihood of Type I error 12. Which of the following best describes a null hypothesis?\ a) There is no effect or difference\ b) There is an effect or difference\ c) The sample mean is higher than the population mean\ d) The sample mean is lower than the population mean 13. In a one-sample t-test, which of the following is required?\ a) Population mean\ b) Population standard deviation\ c) Sample size\ d) All of the above 14. What does Cohen's d measure?\ a) The effect size\ b) The confidence interval width\ c) The probability of a Type I error\ d) The z-score 15. Which value of Cohen's d represents a large effect size?\ a) 0.2\ b) 0.5\ c) 0.8\ d) 1.0 16. The critical value of t in a two-tailed t-test depends on:\ a) The sample mean\ b) The degrees of freedom (df)\ c) The p-value\ d) The standard error 17. In hypothesis testing, the alpha level is:\ a) The probability of making a Type II error\ b) The significance level chosen for the test\ c) The confidence level chosen for the test\ d) The probability of obtaining a sample mean 18. A sample mean is an example of:\ a) A statistic\ b) A parameter\ c) A random variable\ d) An effect size 19. What is the purpose of a t-test?\ a) To measure the effect size\ b) To compare the means of two groups\ c) To describe variability in a sample\ d) To calculate the confidence interval 20. What is the effect of increasing the alpha level from 0.01 to 0.05?\ a) Increased probability of Type I error\ b) Increased probability of Type II error\ c) Decreased power\ d) No effect on Type I error 21. What is a key assumption of an independent samples t-test?\ a) Equal variances between groups\ b) Paired data\ c) A normal distribution\ d) A large sample size 22. A confidence interval provides:\ a) A range of values for the sample mean\ b) A range of values for the population mean\ c) The probability that the sample mean lies in the interval\ d) The difference between sample means 23. If the null hypothesis falls inside the confidence interval, what should you do?\ a) Reject the null hypothesis\ b) Fail to reject the null hypothesis\ c) Accept the null hypothesis\ d) Accept the alternative hypothesis 24. Which of the following factors affects the width of a confidence interval?\ a) Sample size (N)\ b) Variability in the data\ c) The confidence level\ d) All of the above 25. Which test would you use to compare means from the same group at two different times?\ a) Independent samples t-test\ b) Paired samples t-test\ c) One-sample t-test\ d) Chi-square test 26. The standard deviation is a measure of:\ a) Central tendency\ b) Spread or variability\ c) Sampling error\ d) Confidence interval width 27. What is the null hypothesis in an independent samples t-test?\ a) The means of the two groups are equal\ b) The means of the two groups are different\ c) The means of the two groups are greater than 0\ d) The standard deviations of the two groups are equal 28. What does a p-value of.01 mean?\ a) The probability that the null hypothesis is false\ b) The probability that the null hypothesis is true\ c) The probability of obtaining the observed result, assuming the null hypothesis is true\ d) The probability of making a Type II error 29. If the sample size increases, what happens to the standard error?\ a) It increases\ b) It decreases\ c) It stays the same\ d) It equals the standard deviation 30. What does a one-sample t-test compare?\ a) The sample mean to a known population mean\ b) The sample mean to another sample mean\ c) The sample median to the population median\ d) The standard deviations of two samples 31. Which value indicates a stronger relationship in a correlation coefficient?\ a) 0.5\ b) -0.7\ c) 0.3\ d) 0.1 32. A t-test is considered significant when:\ a) The t-value exceeds the critical t-value\ b) The p-value is greater than the significance level\ c) The confidence interval includes zero\ d) The t-value equals the sample mean 33. What is the relationship between sample size and margin of error?\ a) Larger sample size increases margin of error\ b) Larger sample size decreases margin of error\ c) Sample size has no effect on margin of error\ d) Sample size and margin of error are unrelated 34. The Central Limit Theorem states that:\ a) The sampling distribution of the sample mean approaches normality as sample size increases\ b) The population distribution is always normally distributed\ c) The standard error of the mean increases with larger samples\ d) The population mean equals the sample mean 35. In which situation would you use a paired-sample t-test?\ a) Comparing the average of two unrelated groups\ b) Comparing the same group's performance before and after an intervention\ c) Comparing two different groups measured at different times\ d) Comparing population variances 36. The degrees of freedom for a t-test depend on:\ a) The number of groups in the study\ b) The sample size\ c) The significance level\ d) The p-value 37. Which of the following increases the likelihood of making a Type II error?\ a) Increasing sample size\ b) Decreasing sample size\ c) Increasing the alpha level\ d) Decreasing the confidence level 38\. Which of the following best describes an alternative hypothesis? a\) A statement that there is no effect or difference b\) A statement that there is an effect or difference c\) A statement that the sample mean equals the population mean d\) A statement that the sample mean equals zero 39\. Which of the following is true about a one-tailed hypothesis test? a\) It tests for an effect in both directions b\) It has less power than a two-tailed test c\) It tests for an effect in one specific direction d\) It has a higher chance of committing a Type I error 40\. If a 95% confidence interval for the difference between two sample means includes zero, what conclusion can you draw? a\) Reject the null hypothesis b\) Fail to reject the null hypothesis c\) The sample means are significantly different d\) The sample means are the same 41\. The term \"degrees of freedom\" refers to: a\) The number of scores in a sample that are free to vary b\) The number of variables in a data set c\) The sample size divided by the population size d\) The standard error divided by the sample size 42\. What is the purpose of calculating effect size? a\) To determine the direction of a relationship b\) To measure the magnitude of an observed effect c\) To calculate the significance level d\) To determine the p-value 43\. In a two-tailed test, the alpha level of 0.05 is split: a\) 50% on each tail b\) 2.5% on each tail c\) 10% on each tail d\) 0.05% on each tail 44\. In a paired-sample t-test, the null hypothesis assumes that: a\) The means of two independent groups are equal b\) The difference between paired observations is zero c\) The mean difference between the two groups is not zero d\) The variance between the groups is the same 45\. If you are comparing the means of three or more groups, which statistical test should you use? a\) Independent t-test b\) One-sample t-test c\) Analysis of Variance (ANOVA) d\) Paired-sample t-test 46\. Which of the following best describes homogeneity of variance? a\) The variances in different groups are equal b\) The sample mean is equal to the population mean c\) The standard deviation in one sample is zero d\) The means of different groups are equal 47\. When conducting a hypothesis test, the alternative hypothesis is typically denoted by: a\) H1 b\) H0 c\) P d\) Z 48\. In a normal distribution, what percentage of data falls within one standard deviation of the mean? a\) 50% b\) 68% c\) 95% d\) 99% 49\. The t-distribution is used instead of the z-distribution when: a\) The sample size is large b\) The sample size is small and/or population standard deviation is unknown c\) The population mean is unknown d\) The sample mean is unknown 50\. In an ANOVA test, a significant result suggests: a\) There is no difference between the groups b\) At least one group mean is significantly different from the others c\) All group means are equal d\) The standard deviations between groups are equal \-\-- \#\#\# \*\*Answer Key\*\* 1\. c 2\. d 3\. b 4\. b 5\. a 6\. b 7\. b 8\. a 9\. c 10\. c 11\. a 12\. a 13\. d 14\. a 15\. c 16\. b 17\. b 18\. a 19\. b 20\. a 21\. a 22\. b 23\. b 24\. d 25\. b 26\. b 27\. a 28\. c 29\. b 30\. a 31\. b 32\. a 33\. b 34\. a 35\. b 36\. b 37\. b 38\. b 39\. c 40\. b 41\. a 42\. b 43\. b 44\. b 45\. c 46\. a 47\. a 48\. b 49\. b 50\. b