Research Methods & Data Analysis in
Psychology II Quiz review University of Iowa
EXAM 2 (Gupta)
Having committed yourself to a one-tailed test, the formal statement if the null
hypothesis should be expanded to include values of the population
mean ...ANSWER...more deviant than the critical z
The advantage of a one-tailed test is that it increases the likelihood of detecting
a ...ANSWER...false null hypothesis in the direction of concern
You complete an upper one-tailed hypothesis test using a significance level of .05, and
based on the evidence from the sample, your decision is to reject the null hypothesis,
p= .02. What is the p-value? ...ANSWER...The probability of getting the observed
sample value or a more extreme one, from the H0 population
Which of the following is an accurate definition of effect size? ...ANSWER...a measure
of the absolute magnitude of the observed effect/difference, independent of the sample
size and standard error of the mean
Under what circumstances can a very small sample effect still be
significant? ...ANSWER...If the sample is very large
When is there a risk of a Type I error? ...ANSWER...Whenever H0 is rejected
Which of the following is an accurate definition for the power of a statistical
test? ...ANSWER...The probability of rejecting a false null hypothesis
, If a hypothesis test is found to have power = 0.70, what is the probability that the test
will result in a Type II error? ...ANSWER...0.30
A pollster reports, with 95 percent confidence, that between 55 and 61 percent of all
Americans favor mandatory drug testings for employees in positions of public trust (bus
drivers, airline pilots, etc). The point estimate for the unknown population proportion
(who favor mandatory drug testing) equals ...ANSWER...58 percent.
Prior to attending college, randomly selected college-bound students participate in a
summer workshop on the development of good study habits. Subsequently, at the end
of their first year in college, they showed a dramatic increase in grade point averages,
relative to the national average of 2.75, as revealed by a 95 percent confidence interval
of 2.90 to 3.30. This confidence interval signifies that ...ANSWER...we can be
reasonably confident that the true population mean (for all students who could
conceivably take the summer workshop) is between 2.90 and 3.30.
A sample of n = 25 scores produces a t statistic of t = -2.062. If the researcher is using a
two-tailed test, which of the following is the correct statistical
decision? ...ANSWER...The researcher must fail to reject the null hypothesis with either
alpha = .05 or alpha = .01.
A pollster reports, with 95 percent confidence, that between 55 and 61 percent of all
Americans favor mandatory drug testings for employees in positions of public trust (bus
drivers, airline pilots, etc). The boundaries of this confidence interval (55 to 61 percent)
suggest that ...ANSWER...a majority of Americans probably favor mandatory drug
testing.
When n is small (less than 30), how does the shape of the t distribution compare to the
normal distribution? ...ANSWER...It is flatter and more spread out than the normal
distribution
Any shift to a higher confidence level produces a ...ANSWER...wider, less precise
confidence interval
The t distribution is most different from the standard normal distribution when sample
size is ...ANSWER...very small
Psychology II Quiz review University of Iowa
EXAM 2 (Gupta)
Having committed yourself to a one-tailed test, the formal statement if the null
hypothesis should be expanded to include values of the population
mean ...ANSWER...more deviant than the critical z
The advantage of a one-tailed test is that it increases the likelihood of detecting
a ...ANSWER...false null hypothesis in the direction of concern
You complete an upper one-tailed hypothesis test using a significance level of .05, and
based on the evidence from the sample, your decision is to reject the null hypothesis,
p= .02. What is the p-value? ...ANSWER...The probability of getting the observed
sample value or a more extreme one, from the H0 population
Which of the following is an accurate definition of effect size? ...ANSWER...a measure
of the absolute magnitude of the observed effect/difference, independent of the sample
size and standard error of the mean
Under what circumstances can a very small sample effect still be
significant? ...ANSWER...If the sample is very large
When is there a risk of a Type I error? ...ANSWER...Whenever H0 is rejected
Which of the following is an accurate definition for the power of a statistical
test? ...ANSWER...The probability of rejecting a false null hypothesis
, If a hypothesis test is found to have power = 0.70, what is the probability that the test
will result in a Type II error? ...ANSWER...0.30
A pollster reports, with 95 percent confidence, that between 55 and 61 percent of all
Americans favor mandatory drug testings for employees in positions of public trust (bus
drivers, airline pilots, etc). The point estimate for the unknown population proportion
(who favor mandatory drug testing) equals ...ANSWER...58 percent.
Prior to attending college, randomly selected college-bound students participate in a
summer workshop on the development of good study habits. Subsequently, at the end
of their first year in college, they showed a dramatic increase in grade point averages,
relative to the national average of 2.75, as revealed by a 95 percent confidence interval
of 2.90 to 3.30. This confidence interval signifies that ...ANSWER...we can be
reasonably confident that the true population mean (for all students who could
conceivably take the summer workshop) is between 2.90 and 3.30.
A sample of n = 25 scores produces a t statistic of t = -2.062. If the researcher is using a
two-tailed test, which of the following is the correct statistical
decision? ...ANSWER...The researcher must fail to reject the null hypothesis with either
alpha = .05 or alpha = .01.
A pollster reports, with 95 percent confidence, that between 55 and 61 percent of all
Americans favor mandatory drug testings for employees in positions of public trust (bus
drivers, airline pilots, etc). The boundaries of this confidence interval (55 to 61 percent)
suggest that ...ANSWER...a majority of Americans probably favor mandatory drug
testing.
When n is small (less than 30), how does the shape of the t distribution compare to the
normal distribution? ...ANSWER...It is flatter and more spread out than the normal
distribution
Any shift to a higher confidence level produces a ...ANSWER...wider, less precise
confidence interval
The t distribution is most different from the standard normal distribution when sample
size is ...ANSWER...very small
