Psych 100a: Quiz 9 - Paired-Samples t

Which of the following research scenarios would require a paired-samples t-test? Select one: a. Identical twins are compared to see whether they differ in their temperament b. To examine test bias, an educational researcher compares test scores between males and females c. Smokers and non-smokers are given a survey to assess their attitudes toward smoking d. Treatment and control participants are compared to determine which group has lower anxiety

a. Identical twins are compared to see whether they differ in their temperament

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. One a 10-point frequency scale, he finds a alcohol mean of 4.5 at age 16 and a mean of 7 at age 18, for a mean difference (change) of 2.5. The 95% confidence interval for the mean change ranges from 1.5 to 3.5. Which of the following population parameters is supported (i.e., are plausible) based on this interval. CHECK ALL THAT APPLY. Select one: a. 1.7 b. -2.5 c. 3.4 d. 0 e. 5

a. 1.7 c. 3.4

A test preparation company reports that, after taking their GRE preparation class, student scores increased. Which of the following sets of descriptive statistics would produce the largest standardized mean difference? Select one: a. GRE pretest mean = 625 (SD = 100), posttest mean = 500 (SD = 100) b. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50) c. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200) d. GRE pretest mean = 625 (SD = 150), posttest mean = 500 (SD = 150)

b. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50)

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. The average increase in alcohol use scores was .30 points, and a paired-samples t test gave a probability value of .15 (15%). Which of the following interpretations is correct regarding the probability value? Select one: a. If there is truly no change in the population, an increase of .30 or more would occur in 15% of all random samples from such a population b. If there is truly a difference or change in the population, an increase of .30 more would occur in 15% of all random samples from such a population c. There is a 15% probability that the null hypothesis is true in the population d. A difference of .30 has a 15% probability of occurring due to random chance

a. If there is truly no change in the population, an increase of .30 or more would occur in 15% of all random samples from such a population

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 77 points, and a paired-samples t test gave a probability value of .005 (.5% or one half of one percent). Which of the following interpretations is correct regarding these results? Select one: a. If there is truly no difference in the population, a change of 77 points or more would occur in .5% of all random samples from such a population b. If there is truly a difference in the population, an increase of 77 points or more would occur in .5% of all random samples from such a population Incorrect c. There is a .5% probability that the null hypothesis is true in the population d. A difference of 77 points has a .5% probability of occurring due to random chance

a. If there is truly no difference in the population, a change of 77 points or more would occur in .5% of all random samples from such a population

Which of the following is NOT an example of a within-subjects design? Select one: a. Males and females are compared to see whether they differ in their depression levels b. Students rate the appropriateness of texting in class and texting while on the phone, and the mean ratings are compared Incorrect c. Identical twins are compared to see whether they differ in their temperament d. Pretest and posttest scores are obtained from a group of people prior to and after they participate in an intervention

a. Males and females are compared to see whether they differ in their depression levels

A researcher wants to study the effectiveness of a smoking cessation intervention. Which of the following research designs would require a paired-samples t-test as the analysis? Select one: a. Recruit a sample of 50 smokers, measure their smoking frequency, conduct the intervention, then measure their smoking frequency. Compare the average smoking frequency before and after the intervention. b. Recruit a sample of 50 smokers, assign half to receive the intervention, and assign the other half to receive a placebo. Compare the average smoking frequency between the two groups.

a. Recruit a sample of 50 smokers, measure their smoking frequency, conduct the intervention, then measure their smoking frequency. Compare the average smoking frequency before and after the intervention.

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 52 in 7th and 8th grade, respectively. The standard error for the paired-samples t-statistic is 2.25. Which of the following conclusions is true regarding the change in scores? Select one: a. The change in scores from 7th to 8th grade is no larger than what you would expect due to random chance b. The change in scores from 7th to 8th grade is larger than what is expected due to random chance c. The change in scores from 7th to 8th grade is a large improvement d. Results are inconclusive; scores may or may not have significantly changed

a. The change in scores from 7th to 8th grade is no larger than what you would expect due to random chance

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. The pre-test and post-test means are 7 and 5, respectively. The standard error for the paired-samples t-statistic is .50. Which of the following conclusions is true regarding the change in smoking behavior? Select one: a. The change in smoking frequency is larger than what is expected due to random chance b. The change in smoking frequency is in the opposite direction of the researcher's hypothesis c. The change in smoking frequency is no larger than what you would expect due to random chance d. Results are inconclusive; scores may or may not have significantly changed

a. The change in smoking frequency is larger than what is expected due to random chance

An educational psychologist is interested in whether math test scores improve between 7th and 8th grade. She recruits a sample of 100 students and uses a paired-samples t-test to analyze the data. Which of the following is a valid null hypothesis for the study? Select one: a. The difference between the average 7th and 8th grade math scores is 0 in the population b. The difference between the average 7th and 7th grade math scores is positive (scores improve) in the sample c. The difference between the average 7th and 7th grade math scores is positive (scores improve) in the population d. The difference between the average 7th and 8th grade math scores is 0 in the sample

a. The difference between the average 7th and 8th grade math scores is 0 in the population

An educational psychologist is interested in whether math test scores improve between 7th and 8th grade. She recruits a sample of 100 students and uses a paired-samples t-test to analyze the data. Which of the following is a valid null hypothesis for the study? Select one: a. The difference between the average 7th and 8th grade math scores is 0 in the population b. The difference between the average 7th and 8th grade math scores is 0 in the sample c. The difference between the average 7th and 7th grade math scores is positive (scores improve) in the sample d. The difference between the average 7th and 7th grade math scores is positive (scores improve) in the population

a. The difference between the average 7th and 8th grade math scores is 0 in the population

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively, for an average change of 3. The 95% confidence interval for the mean change is 1 to 6. Which of the following is true? Select one: a. There is a 95% probability that the interval from 1 to 6 contains the true mean change in the population b. 95% percent of random samples would yield a mean change between 1 and 6 c. There is a 95% probability that the interval from 1 to 6 contains the mean change in the sample d. 95% of the means in the population range between 1 to 6 e. There is a 95% probability that repeating the study would give a new estimate of the mean change between 1 to 6

a. There is a 95% probability that the interval from 1 to 6 contains the true mean change in the population

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. The average increase in alcohol use scores was .30 points, and a paired-samples t test gave a probability value of .01 (1%). Which of the following interpretations is correct regarding these results? Select one: a. There is a reliable increase in alcohol use between the ages of 16 and 18 b. Alcohol use is steady and does not change between the ages of 16 and 18 c. A .30 increase represents random chance fluctuation as opposed to a true difference

a. There is a reliable increase in alcohol use between the ages of 16 and 18

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. The pre-test and post-test means are 7 and 5, respectively, for a mean change of -2. The 95% confidence interval for the mean change is -1.5 to -2.5. Which of the following population parameters is supported (i.e., are plausible) based on this interval. CHECK ALL THAT APPLY. Select one or more: a. 0 b. -1.7 c. 2 d. -2.5 e. -3.6

b. -1.7 d. -2.5

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. The average increase in alcohol use scores was .30 points, and a paired-samples t test gave a probability value of .15 (15%). Which of the following interpretations is correct regarding these results? Select one: a. A .30 increase represents a true difference in the population b. Alcohol use is steady and does not change between the ages of 16 and 18 c. There is a reliable increase in alcohol use between the ages of 16 and 18

b. Alcohol use is steady and does not change between the ages of 16 and 18

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 12 points, and a paired-samples t test gave a probability value of .09 (9%). Which of the following interpretations is correct regarding these results? Select one: a. There is a reliable difference in energy expenditure between the two active video games b. Energy expenditure is steady and does not change between the two games c. The two types of video games produce differences in energy expenditure

b. Energy expenditure is steady and does not change between the two games

A test preparation company reports that, after taking their GRE preparation class, student scores increased. Which of the following sets of descriptive statistics would produce the largest standardized mean difference? Select one: a. GRE pretest mean = 625 (SD = 150), posttest mean = 500 (SD = 150) b. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50) c. GRE pretest mean = 625 (SD = 100), posttest mean = 500 (SD = 100) d. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200)

b. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50)

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively. The standard error for the paired-samples t-statistic is 2. Which of the following interpretations is true regarding the standard error? Select one: a. A change of 3 points between 7th and 8th grade has a t-statistic of 2 or greater b. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 2 points, on average c. The alternate hypothesis predicts a 2-point change in scores d. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 3 points, on average

b. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 2 points, on average

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. The average increase in alcohol use scores was .30 points, and a paired-samples t test gave a probability value of .01 (1%). Which of the following interpretations is correct regarding the probability value? Select one: a. If there is truly a difference or change in the population, an increase of .30 would occur in 1% of all random samples from such a population b. If there is truly no change in the population, an increase of .30 would occur in 1% of all random samples from such a population c. A difference of .30 has a 1% probability of occurring due to random chance d. There is a 1% probability that the null hypothesis is true in the population

b. If there is truly no change in the population, an increase of .30 would occur in 1% of all random samples from such a population

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 12 points, and a paired-samples t test gave a probability value of .09 (9%). Which of the following interpretations is correct regarding these results? Select one: a. There is a 9% probability that the null hypothesis is true in the population b. If there is truly no difference in the population, a change of 12 points or more would occur in 9% of all random samples from such a population c. If there is truly a difference in the population, an increase of 12 points or more would occur in 9% of all random samples from such a population d. A difference of 12 points has a 9% probability of occurring due to random chance

b. If there is truly no difference in the population, a change of 12 points or more would occur in 9% of all random samples from such a population

Which of the following is an example of a within-subjects design? Select one: a. Males and females are compared to see whether they differ in their depression levels b. Pretest and posttest scores are obtained from a group of people prior to and after they participate in a smoking cessation intervention c. Treatment and control participants are compared to determine which group has lower anxiety d. Smokers and non-smokers are given a survey to assess their attitudes toward smoking

b. Pretest and posttest scores are obtained from a group of people prior to and after they participate in a smoking cessation intervention

Which of the following procedures is consistent with a within-subjects design? Select one: a. Take a sample, assign half of the subjects to the treatment, half to the control b. Take a sample, give all subjects a pretest before treatment, expose all to the treatment, then test all subjects a second time after treatment

b. Take a sample, give all subjects a pretest before treatment, expose all to the treatment, then test all subjects a second time after treatment

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively. The paired-samples t-statistic is 1.85 and has a probability value of .08. Which of the following conclusions is true regarding the change in scores? Select one: a. The change in scores from 7th to 8th grade is a large improvement b. The change in scores from 7th to 8th grade is not larger than what you would expect due to random chance c. The change in scores from 7th to 8th grade is larger than what is expected due to random chance d. Results are inconclusive; scores may or may not have significantly changed

b. The change in scores from 7th to 8th grade is not larger than what you would expect due to random chance

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively, for an average change of 3. The 95% confidence interval for the mean change is -1 to 7. Which of the following is true? Select one: a. The confidence interval tells us nothing about the change in the population b. There is a high probability that scores did not change if the study was performed on the entire population c. There is a high probability that scores improved if the study was performed on the entire population

b. There is a high probability that scores did not change if the study was performed on the entire population

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 77 points, and a paired-samples t test gave a probability value of .005 (.5% or one half of one percent). Which of the following interpretations is correct regarding these results? Select one: a. Energy expenditure is steady and does not change between the two games b. There is a reliable difference in energy expenditure between the two active video games c. The difference in energy expenditure between the games could reasonably occur due to random chance

b. There is a reliable difference in energy expenditure between the two active video games

Which of the following is NOT an example of a within-subjects design? Select one: a. An educational researcher compares the change in test scores for a sample of students between 7th and 8th grade Incorrect b. To examine test bias, an educational researcher compares test scores between Hispanics and Caucasians c. Husband and wife pairs are compared to see which gender reports the highest level of marital satisfaction d. Students in a social psychology experiment rate the competency of female professors dressed in business attire, then they rate the competency of female professors dressed in casual attire

b. To examine test bias, an educational researcher compares test scores between Hispanics and Caucasians

A psychologist is studying marital satisfaction, and she wants to determine whether husbands or wives report higher satisfaction. She recruits a sample of 100 husband-wife pairs and measures marital satisfaction on a 1-10 scale. If she uses a paired-samples t-test to analyze the data, which of the following sets of means provides the MOST evidence in support of the alternate hypothesis? Check all that apply. Select one: a. Husband mean = 7, wife mean = 7 b. Husband mean = 8, wife mean = 7.9 c. Husband mean = 5, wife mean = 7

c. Husband mean = 5, wife mean = 7

A test preparation company reports that, after taking their GRE preparation class, student scores increased. Which of the following sets of descriptive statistics would produce the smallest standardized mean difference? Select one: a. GRE pretest mean = 625 (SD = 150), posttest mean = 500 (SD = 150) b. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50) c. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200) d. GRE pretest mean = 625 (SD = 100), posttest mean = 500 (SD = 100)

c. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200)

A psychologist is studying marital satisfaction, and she wants to determine whether husbands or wives report higher satisfaction. She recruits a sample of 100 husband-wife pairs and measures marital satisfaction on a 1-10 scale. If she uses a paired-samples t-test to analyze the data, which of the following sets of means provides the MOST evidence in support of the null hypothesis? Check all that apply. Select one: a. Husband mean = 8, wife mean = 7.9 b. Husband mean = 5, wife mean = 7 c. Husband mean = 7, wife mean = 7

c. Husband mean = 7, wife mean = 7

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively. The standard error for the paired-samples t-statistic is 2. Which of the following interpretations is true regarding the standard error? Select one: a. A change of 3 points between 7th and 8th grade has a t-statistic of 2 or greater Incorrect b. The alternate hypothesis predicts a 2-point change in scores c. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 2 points, on average d. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 3 points, on average

c. If the null hypothesis is true in the population, random chance (sampling error) would cause a difference of 2 points, on average

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 77 points, and a paired-samples t test gave a probability value of .005 (.5% or one half of one percent). Which of the following interpretations is correct regarding these results? Select one: a. A difference of 77 points has a .5% probability of occurring due to random chance b. There is a .5% probability that the null hypothesis is true in the population c. If there is truly no difference in the population, a change of 77 points or more would occur in .5% of all random samples from such a population d. If there is truly a difference in the population, an increase of 77 points or more would occur in .5% of all random samples from such a population

c. If there is truly no difference in the population, a change of 77 points or more would occur in .5% of all random samples from such a population

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. Which of the following sets of means provides the strongest support for the researcher's prediction? Select one: a. Pre-test mean = 7, post-test mean = 7.25 b. Pre-test mean = 7, post-test mean = 5.50 c. Pre-test mean = 7, post-test mean = 3.25 d. Pre-test mean = 7, post-test mean = 8.50

c. Pre-test mean = 7, post-test mean = 3.25

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively. The paired-samples t-statistic is 1.85 and has a probability value of .04. Which of the following conclusions is true regarding the change in scores? Select one: a. The change in scores from 7th to 8th grade is a large improvement b. Results are inconclusive; scores may or may not have significantly changed c. The change in scores from 7th to 8th grade is larger than what is expected due to random chance d. The change in scores from 7th to 8th grade is not larger than what you would expect due to random chance

c. The change in scores from 7th to 8th grade is larger than what is expected due to random chance

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. The pre-test and post-test means are 7 and 5, respectively. The standard error for the paired-samples t-statistic is .50. Which of the following conclusions is true regarding the change in smoking behavior? Select one: a. The change in smoking frequency is in the opposite direction of the researcher's hypothesis b. Results are inconclusive; scores may or may not have significantly changed c. The change in smoking frequency is larger than what is expected due to random chance d. The change in smoking frequency is no larger than what you would expect due to random chance

c. The change in smoking frequency is larger than what is expected due to random chance

A test preparation company runs a study to determine whether their course improves GRE scores. Students take a test comprised of GRE-type items, then they participate in the test prep class. After completing the class, they take a post-test GRE test. The company reports that, after taking their GRE preparation class, student scores increased by a magnitude that is equivalent to .25 standard deviation units. Which of the following is true? Select one: a. The test prep class produced a non-significant improvement in scores b. The test prep class produced a significant improvement in scores c. The test prep class produced a relatively small improvement in scores d. The test prep class produced a large improvement in scores e. The test prep class produced virtually no improvement in scores

c. The test prep class produced a relatively small improvement in scores

An educational psychologist is interested in whether test scores improve between 7th and 8th grade. She recruits a sample of 100 students and finds test score averages of 50 and 53 in 7th and 8th grade, respectively, for an average change of 3. The 95% confidence interval for the mean change is 1 to 6. Which of the following is true? Select one: a. There is a 95% probability that the interval from 1 to 6 contains the mean change in the sample b. There is a 95% probability that repeating the study would give a new estimate of the mean change between 1 to 6 c. There is a 95% probability that the interval from 1 to 6 contains the true mean change in the population d. 95% of the means in the population range between 1 to 6 e. 95% percent of random samples would yield a mean change between 1 and 6

c. There is a 95% probability that the interval from 1 to 6 contains the true mean change in the population

A clinical psychologist is studying the progression of alcohol use in a teenage population. She collects a measure of alcohol use from the same group of teens at ages 16 and 18. One a 10-point frequency scale, he finds a alcohol mean of 4.5 at age 16 and a mean of 7 at age 18, for a mean difference (change) of 2.5. The 95% confidence interval for the mean change ranges from 1.5 to 3.5. Which of the following is true? Select one: a. 95% percent of random samples would yield a mean change between 1.5 and 3.5 b. There is a 95% probability that repeating the study would give a new estimate of the mean change between 1.5 and 3.5 c. There is a 95% probability that the interval from 1.5 to 3.5 contains the true mean change in the population d. There is a 95% probability that the interval from 1.5 to 3.5 contains the mean change in the sample e. 95% of the means in the population range between 1.5 and 3.5

c. There is a 95% probability that the interval from 1.5 to 3.5 contains the true mean change in the population

An exercise physiologist is studying energy exertion from playing video games. Participants first play Wii bowling for 15 minutes, during which researchers measure calories burned. After a period of rest, participants then play Will tennis. The average change in energy expenditure scores was 77 points, and a paired-samples t test gave a probability value of .005 (.5% or one half of one percent). Which of the following interpretations is correct regarding these results? Select one: a. Energy expenditure is steady and does not change between the two games b. The difference in energy expenditure between the games could reasonably occur due to random chance c. There is a reliable difference in energy expenditure between the two active video games

c. There is a reliable difference in energy expenditure between the two active video games

Which of the following research scenarios would require a paired-samples t-test? Select one: a. Smokers and non-smokers are given a survey to assess their attitudes toward smoking b. To examine test bias, an educational researcher compares test scores between males and females c. Treatment and control participants are compared to determine which group has lower anxiety d. Identical twins are compared to see whether they differ in their temperament

d. Identical twins are compared to see whether they differ in their temperament

A test preparation company reports that, after taking their GRE preparation class, student scores increased by a magnitude that is equivalent to .25 standard deviation units. Which of the following sets of descriptive statistics produced this effect size? Select one: a. GRE pretest mean = 625 (SD = 100), posttest mean = 500 (SD = 100) b. GRE pretest mean = 525 (SD = 100), posttest mean = 500 (SD = 100) Incorrect c. GRE pretest mean = 575 (SD = 100), posttest mean = 500 (SD = 100) d. GRE pretest mean = 475 (SD = 100), posttest mean = 500 (SD = 100)

d. GRE pretest mean = 475 (SD = 100), posttest mean = 500 (SD = 100)

A test preparation company reports that, after taking their GRE preparation class, student scores increased. Which of the following sets of descriptive statistics would produce the smallest standardized mean difference? Select one: a. GRE pretest mean = 625 (SD = 150), posttest mean = 500 (SD = 150) b. GRE pretest mean = 625 (SD = 100), posttest mean = 500 (SD = 100) c. GRE pretest mean = 625 (SD = 50), posttest mean = 500 (SD = 50) d. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200)

d. GRE pretest mean = 625 (SD = 200), posttest mean = 500 (SD = 200)

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. The pre-test and post-test means are 7 and 5, respectively. The standard error for the paired-samples t-statistic is .50. Which of the following conclusions is true regarding the standard error? Select one: a. An effective intervention would change scores by at least .50 points b. The null hypothesis predicts a change of .50 c. A change of two points or more could occur 50% of the time due to random chance alone d. Random chance (sampling error) would produce a difference of .50, even if the intervention is ineffective

d. Random chance (sampling error) would produce a difference of .50, even if the intervention is ineffective

A psychologist is interested in determining whether a new treatment for depression impacts depression scores. She recruits 30 subjects and measures their depression at baseline then again following the intervention. At the conclusion of the study she uses a paired-samples t-test to evaluate whether the groups differ. The t-statistic is 1.90 with a probability of .0624. Which of the following conclusions is true regarding the treatment? Select one: a. Results are inconclusive; the intervention may or may not have worked b. The treatment improves scores beyond what is expected due to random chance c. The treatment produced a large decrease in depression relative to the baseline condition d. The treatment changed scores in a manner that is consistent with random chance

d. The treatment changed scores in a manner that is consistent with random chance

A psychologist is interested in determining whether a new treatment for depression impacts depression scores. She recruits 30 subjects and measures their depression at baseline then again following the intervention. At the conclusion of the study she uses a paired-samples t-test to evaluate whether the groups differ. The t-statistic is 1.90 with a one-tailed probability of .031. Which of the following conclusions is true regarding the treatment? Select one: a. Results are inconclusive; the intervention may or may not have worked b. The treatment changed scores in a manner that is consistent with random chance c. The treatment produced a large decrease in depression relative to the control group d. The treatment improves scores beyond what is expected due to random chance

d. The treatment improves scores beyond what is expected due to random chance

A psychologist is interested in whether participation in a smoking cessation intervention reduces smoking. She recruits a sample of 50 participants and has them rate their smoking frequency on a 1-10 scale. The pre-test and post-test means are 7 and 5, respectively, for a mean change of -2. The 95% confidence interval for the mean change is -3.5 to -.5. Which of the following is true? Select one: a. There is a 95% probability that the interval from -3.5 to -.5 contains the mean change in the sample b. 95% of the means in the population range between -3.5 to -.5 c. 95% percent of random samples would yield a mean change between -3.5 to -.5 d. There is a 95% probability that the interval from -3.5 to -.5 contains the true mean change in the population e. There is a 95% probability that repeating the study would give a new estimate of the mean change between -3.5 to -.5

d. There is a 95% probability that the interval from -3.5 to -.5 contains the true mean change in the population