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

Q: A t-test and a z-test calculation differs due to _______
- the use of the sample standard deviation for the t-test and the population standard deviation for the z-test.
- the use of an educated guess for the standard deviation for a  t-test whereas the z-test does not require a standard deviation.
- the use of N-1 for the standard error calculation in the t-test, but N is used for the z-test.
- iterative procedures for the t-test, resulting in answers that converge whereas in z-tests there is certainty of calculation accuracy from the start.
A: the use of the sample standard deviation for the t-test and the population standard deviation for the z-test.

Q: For a single sample z or t-test, what is the mean used in the null hypothesis?
- A standard or normal value for a mean, \(\mu\)μ, that is established and understood.
- A guess of the value for a population mean,\(\mu\)μ.
- zero.
A: A standard or normal value for a mean, \(\mu\)μ, that is established and understood.

Q: For the distribution of all possible sample means for any specific sample size, we can calculate a standard deviation. What do we name that standard deviation?
- the standard error
- the standard extants
- the distribution of means
- the estimate of modality
A: the standard error

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: Generally, degrees of freedom is __________
- the number of scores in the sample minus the number of constraints
- the maximum score in the sample minus the number of constraints
- the number of scores in the sample minus those in excess of requirements of the test.
- the number of scores minus those with scores in the sample beyond one standard deviation.
A: the number of scores in the sample minus the number of constraints

Q: A researcher developed a driving error reduction method (DERM) intended to be used for driving education classes. The number of errors for students in the final driving simulator test for those in the DERM condition compared to the Usual condition were recorded. The means of these two groups were compared yielding the following results.

M_DERM: 2.43

M_Usual: 4.62

t (21) = 2.43, p = .024

Which of the below sentences is the best interpretation?
- The sample evidence is sufficient to support DERM is effective and reduces the number of errors in the driving simulator test.
- The sample evidence is insufficient to support DERM is effective, therefore no evidence for reduction in the number of errors in the driving simulator test.
- It is not possible to determine if  DERM is effective and reduces the number of errors in the driving simulator test.
A: The sample evidence is sufficient to support DERM is effective and reduces the number of errors in the driving simulator test.

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 constrained.
A: the means being equal to each other.

Q: In which of the following situations could a paired samples t-test be used? Select all answers that are correct.
- When the scores on a pre-measurement is used to pair similar participants who are then randomly assigned.
- When the persons in the study come into it naturally connected to each other by living situation, blood relations, work partners, etc.
- When each person in the study provides two measurements sequentially.
- When the persons comprising the two groups have been both randomly selected and randomly assigned to their groups.
A: When the scores on a pre-measurement is used to pair similar participants who are then randomly assigned.; When the persons in the study come into it naturally connected to each other by living situation, blood relations, work partners, etc.; When each person in the study provides two measurements sequentially.

Q: Suppose we have done a single sample z-test and calculated z to be 1.32. That z-value corresponds to a probability of .187. What decision should we make?
- We should reject the null hypothesis.
- We should retain the null hypothesis
- We should retain the alternative hypothesis
A: We should retain the null hypothesis

Q: For a single-sample test of a mean, \(\bar{X}\), the reason we use a single-sample t-test rather than a single-sample z-test is we are using the sample standard deviation, \(s\), to _________
- estimate the population standard deviation, \(\sigma\).
- to normalize the mean.
- calculate a Pearson r.
- to test \(\sigma\)'s significance.
A: estimate the population standard deviation, \(\sigma\).

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.

Tori wants to learn about the time over which people recover from major depression. They have reason to think that antidepressant medications speed recovery. They examine the records of a mental health treatment practice and notes the number of months a client is in treatment. Only clients released from treatment by the therapist are included. Tori can then calculate the means and standard deviations  and analyze the data for the 2 groups: Those who received Cognitive Behavioral Therapy (CBT) and those who received CBT with an antidepressant medication added.

What is the correct statistical test for Tori to use to determine if CBT with antidepressants were released from treatment more quickly?
- Independent Samples t-test
- Paired Samples t-test
- Chi-Square Goodness of Fit test
- Chi-Square Test of Independence (Association)
A: Independent Samples t-test

Q: We describe Chi-Square distributions as always being 1-sided tests because _______
- the calculation gives only positive values that get larger as deviation from expected values get larger.
- it lacks a mode.
- is the tangent of the circular version of the z-test.
- the mode is restricted.
A: the calculation gives only positive values that get larger as deviation from expected values get larger.

Q: Which of the following is the correct degrees of freedom ( df ) calculation method for a Chi-Square Test of Independence?
- (Rows – 1) x (Columns – 1)
- (Rows x Columns) – 1
- Observations – 1
- Rows + Columns –2
A: (Rows – 1) x (Columns – 1)

Q: For a Chi-Square Goodness of Fit test, we are trying to determine ______
- If the distribution of observations for the variable differ from a null hypothesis distribution.
- If the distribution of observations differs depending on the level of the other variable.
- If the number of observations is superseded by the degrees of freedom.
- If the mode of the distribution differs from the mean.
A: If the distribution of observations for the variable differ from a null hypothesis distribution.

Q: For a Chi-Square Test of Independence, we are trying to determine _______
- If the distribution of observations differs depending on the level of the other variable.
- If the distribution of observations for the variable differ from a null hypothesis distribution.
- If the mode of the distribution differs from the mean.
- If the number of observations is superseded by the degrees of freedom.
A: If the distribution of observations differs depending on the level of the other variable.

Q: Suppose you read the following in a research report:

"Mean reaction time for primed was M = 0.43 sec., and mean reaction time for unprimed was M = 0.53 sec. An independent samples t-test showed, t (43) = 2.34, p < .05 indicati..."

Strangely, the photocopy you are reading from was badly smudged and you can't read the rest of the sentence. Still you know a lot. Which of the following are correct based on the above? Select all that are correct and avoid responses that are incorrect.
- The means were significantly different.
- The means were not significantly different.
- The scientific hypothesis was supported.
- The scientific hypothesis was not supported.
- The null hypothesis was rejected.
- The null hypothesis was not rejected.
A: The means were significantly different.; The scientific hypothesis was supported.; The null hypothesis was rejected.

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.

Saquan has gathered data for a study examining if a police car parked visibly at a 4-way stop intersection increases the likelihood of people coming to a full stop at the stop signs.

From 1 to 2 PM on a Tuesday a police car was parked at the intersection. From 3 to 4 PM on the same Tuesday no police car was parked at the intersection.

The following data was developed consisting of the number of observations of cars that came to a complete stop or a 'rolling stop' when the police car was present or not.

 | Police Car Present | No Police Car
Full Stop | 48 | 32
Rolling Stop | 15 | 29

Which of the statistical tests below is the correct one to use to analyze this data?
- Independent Samples t-test
- One Sample t-test
- Chi-Square Goodness of Fit test
- Chi-Square Test of Independence (Association)
A: Chi-Square Test of Independence (Association)

Q: Copper has gathered data for a study of the children passing the so-called 'marshmallow test'. ** The experimenter either appeared in a laboratory coat (a symbol of authority and trust) or casual clothing, and was either prompt in returning to a bell rung by the child or not prompt. Then the test with the marshmallow delayed gratification was run with the following results.

 | Lab coat and prompt | Lab coat and not prompt | Casual and prompt | Casual and not prompt
Child waits full time | 28 | 23 | 22 | 15
Child takes marshmallow early | 18 | 23 | 24 | 31

What is the null hypothesis being used as the basis for the statistical calculation?

**Note: The interpretation of this test (children who show ability to delay gratification tend to have better life outcomes) has been called into question by subsequent studies.
- The proportion of children waiting to take the marshmallow does not depend on the dress or behavior of the experimenter.
- The experimenter and child will wait for each other equally.
- Children are equally likely to take the marshmallow as they are to not take the marshmallow.
A: The proportion of children waiting to take the marshmallow does not depend on the dress or behavior of the experimenter.