Title: Exam 3A Chapters 10 and 11
Course: PSYC 301 Statistical Methods in Psychol > Section: Last Part of Course

Q: The difference between a t-test and a z-test calculation is __________
- for the z-test we are given the population standard deviation and for the t-test we must estimate it from our sample.
- for the t-test we have a trustable estimate given by a trusted authority that can be used for the standard deviation.
- the standard deviation is the same for both tests, but for the t-test the standard error is calculated by dividing by N-1.
- in t-tests a trial-and-error approach is used whereas in z-tests there is certainty of procedure from the start.
A: for the z-test we are given the population standard deviation and for the t-test we must estimate it from our sample.

Q: For a single sample test of a mean, \(\bar{X}\), in which we are given both the sample standard deviation, \(s\), and the population standard deviation, \(\sigma\), we will chose to use the _____
- z-test
- t-test
- r-test
- \(\sigma\)-test
A: z-test

Q: For a single sample z or t-test, what is the 'other mean' to which the sample mean is compared?
- A standard or normal value for a mean, \(\mu\), that is established and understood.
- A guess of the value for a population mean,\(\mu\).
- zero.
A: A standard or normal value for a mean, \(\mu\), that is established and understood.

Q: A standard error is _______
- the standard deviation of the distribution of means of samples of a specific size.
- the probability of an error larger than a standard deviation.
- the mistake that is made when deciding to reject a null hypothesis that should be retained.
- the mistake that is made when deciding to retain a null hypothesis that should be rejected.
A: the standard deviation of the distribution of means of samples of a specific size.

Q: In which of the following situations could a paired samples t-test be used? Select all answers that are correct.
- When each person is matched with another person in the other group on another variable.
- When the persons in the study come into it inherently connected to each other.
- When each person in the study provides two measurements sequentially.
- When the persons comprising the two groups have been both selected and assigned randomly.
A: When each person is matched with another person in the other group on another variable.; When the persons in the study come into it inherently connected to each other.; When each person in the study provides two measurements sequentially.

Q: A paired sample t-test can be calculated using which of the following procedures (as long as it is set up correctly)?
- A Single Sample t-test.
- An Independent Samples t-test.
- A Single Sample z-test.
- A Binomial Test.
A: A Single Sample t-test.

Q: You will not just 'recognize' or 'insight' the correct answer to this question. You must think about the various things that are associated with and differentiate among the several kinds of statistical tests we've learned about to make the correct decision.

Charlotte has gather data for a study comparing the number of times students stop while taking online exams under two conditions. The two groups each consisted of 20 students. In one group, students were told that they were being constantly monitored in their taking of the online exam. In the other group students were told they would be randomly monitored a few times during the exam. Charlotte has gotten her data back with the number of times each student stopped in each of the groups, so she can calculate means and standard deviations for each of the groups.

What statistical test of the choices below should she use?
- Independent Samples t-test
- One Sample t-test
- One Sample z-test
- Chi-Square Goodness of Fit test
A: Independent Samples t-test

Q: Suppose we have done a single sample z-test and calculated z to be 2.45. That z-value corresponds to a probability of .007. What decision should we make?
- We should reject the null hypothesis.
- We should retain the null hypothesis
- We should reject the alternative hypothesis
A: We should reject the null hypothesis.

Q: Generally, degrees of freedom is __________
- the number of observations minus the number of constraints.
- the number of observations that are appropriate to use in the analysis.
- the number of participants minus those in excess of requirements of the test.
- the number of participants minus those with scores beyond one standard deviation.
A: the number of observations minus the number of constraints.

Q: You will not just 'recognize' or 'insight' the correct answer to this question. You must think about the various things that are associated with and differentiate among the several kinds of statistical tests we've learned about to make the correct decision.

A casino operating in Gulfport, Mississippi wants to determine if they should offer incentives for persons to come from out-of-state to their casino and hotel on weeknights. To do that, they will take note of the state of issue of license plates on cars entering their parking lot between 6 and 7 PM on weeknights (Sunday through Thursday) and weekend nights (Friday and Saturday). For 2 weekend nights they note the license plates of cars each night and find that of the total of 230 counted cars 80 were from Mississippi and 150 were from other states (Louisiana, Alabama, Florida). On the 5 weeknights they note the license plates of cars showing a total of 250 cars with 120 from Mississippi and 130 from other states.

What is the correct statistical test to determine if there is a difference in the proportion of cars coming from other states on weeknights versus weekend nights?
- Chi-Square Goodness of Fit Test
- Chi-Square Test of Independence
- Independent Samples t-test.
- Single Sample t-test.
A: Chi-Square Test of Independence

Q: For the various t-tests of means, the null hypothesis usually represents ________
- the means being equal to each other.
- the means showing maximum deviation scores.
- the means being not-equal to each other.
- the variance in the means being balanced.
A: the means being equal to each other.

Q: When we write our research reports we describe our statistical tests _________ (select all that are correct)
- without any reference to the null hypothesis.
- describing the null hypothesis and our decision.
- describing the inferences with respect to the research hypothesis.
- excluding the observed descriptive statistics.
A: without any reference to the null hypothesis.; describing the inferences with respect to the research hypothesis.

Q: A researcher developed a new short mood induction method intended to be used for research in which participants must be shifted to a sad mood. This 'TicTok' mood induction measured the mood of persons who saw the sad mood TicToks and the mood of persons who was the happy TicToks. The means of these two groups were compared yielding the following results.

M_sad: 2.43

M_happy: 4.62

t (45) = 3.01, p = .004

Which of the below sentences is the best interpretation?
- The sample evidence is sufficient to support that the new TicTok sad mood induction is effective and makes people feel more sad than persons induced with a happy short video.
- The sample evidence is insufficient to support that the new TicTok mood induction is effective in inducing a sadder mood than happy-toned short videos.
- The sample evidence proves that TicTok videos induce sad moods.
- The sample evidence is inconclusive.
A: The sample evidence is sufficient to support that the new TicTok sad mood induction is effective and makes people feel more sad than persons induced with a happy short video.

Q: Gossett found it necessary to invent the t-test because _______
- he only had a small number of samples of beer and ale compared to large samples for other studies.
- students would find it easier to learn, hence it being called "Student's t"
- of mathematical imbalances in the traditional approaches of the time.
A: he only had a small number of samples of beer and ale compared to large samples for other studies.

Q: Jonny does a Chi-square test of independence with the design below. The study is one of responses to the question "Is the University System of Maryland's decision to require vaccines for Covid for all students, faculty and staff in Fall 2020 a good thing or not a good thing?"

 | Faculty | Staff | Students
Good thing | 220 | 530 | 3540
Not a good thing | 20 | 125 | 730

What is the degrees of freedom for the test? (This is a simple calculation that does not require any calculators, should be done in your head.)
- 2
- 6
- 1
- 3
- 4
- 5
A: 2

Q: Which of the below could be the 'human friendly' version of the null hypothesis for a chi-square goodness of fit test?
- There is an equal probability of people turning left, right, or proceeding straight at the intersection.
- The length of time persons stop for two stop signs at an intersection will be longer than with only one sign.
- Persons will have a mean speed equal to the speed limit on I-68.
- The proportion of people who properly social distance while waiting to enter the store will be the same at Walmart as at Martins grocery.
A: There is an equal probability of people turning left, right, or proceeding straight at the intersection.

Q: By the nature of its distribution, a Chi-square test is always ____
- a one-sided test.
- a two-sided test.
- modally unrestricted.
- modally restricted.
A: a one-sided test.

Q: Suppose you read the following in a research report: "χ^2 (1) = 7.575, p = .006" Which of the following statements are correct?

Select all that are correct, avoid incorrect responses.
- The test was significant.
- The null hypothesis was rejected.
- The scientific hypothesis was not supported.
- The scientific hypothesis was supported.
- The null hypothesis was retained.
- The test was not significant.
A: The test was significant.; The null hypothesis was rejected.; The scientific hypothesis was supported.