Chapter 8 Part 2

Solve Cohen's d: M =3.86 Standard Deviation = 1.26 u = 3.26 sample of 49 Size effect?

0.5, medium size effect

Order the steps of hypothesis testing: ~decide whether to reject or fail to reject the null hypothesis ~draw a random sample, and calculate the sample statistic ~state the hypothesis about the unknown population ~set the criteria for a decision about the unknown population.

4312

Mcritical= A. Uuntreated + Zcritical(σ/√n B. Uuntreated - Zcritical(σ/√n

A

Null Hypothesis, Alternative Hypothesis, or Neither The mean return on common-stock portfolios is different with a trading strategy than with a buy-and-hold strategy.

Alternative

Null or Alternative Hypothesis?? The hypothesis that there is an effect or difference, change, something happened with respect to some characteristic of the underlying populations

Alternative

True or False Cohen's d can be reported as a negative or a positive value.

False, always reported as a positive value

Cohen's d = a. Mtreatment -notreatment/ standard deviation b. Mtreatment + unotreatment/ standard deviation

Mtreatment -notreatment/ standard deviation

Null Hypothesis, Alternative Hypothesis, or Neither The mean return on common-stock portfolios is higher with a trading strategy than with a buy-and-hold strategy.

Neither

Null Hypothesis, Alternative Hypothesis, or Neither The mean return on common-stock portfolios is lower with a trading strategy than with a buy-and-hold strategy.

Neither

Null Hypothesis, Alternative Hypothesis, or Neither The mean return on common-stock portfolios is the same with a trading strategy as with a buy-and-hold strategy.

Null

Null or Alternative Hypothesis?? The hypothesis that there is no effect, no difference, no change, nothing happened with respect to some characteristic of the underlying populations.

Null

A___________ test is used when you predict the direction of the change.

One-tailed

True or False The goal of the hypothesis process is to determine whether there is enough evidence to infer that the alternative hypothesis is true.

True

True or False The testing procedure begins with the assumption that the null hypothesis is true.

True

True or False There are two hypotheses. Null and alternative.

True

A _________ test is used when you do not predict the direction the scores will change.

Two-tailed

The probability of a type I error is_____, and the probability of a type II error is_______. a. α b. β c. 1-α d. 1-β

a. α b. β

Not rejecting HO when HO is true is_________. a. type I error b. correct decision c. type II error

correct decision

Rejecting H0 when H0 is false is_______. a. type I error b. correct decision c. type II error

correct decision

An increase in α (such as using α = .10 instead of α = .05) ____________ (increase, decrease) the power of the z test, because this change in α makes it more likely you will reject the null hypothesis. This change makes it easier to correctly reject a false null hypothesis-meaning that power is increased.

increase

An increase in M _________ (increases, decreases) the power of the z test, because this change in the _______(numerator, denominator) of the test statistic for the z test _________(increases, decreases) the overall test statistic, making it_________(more, less) likely you will reject the null hypothesis.

increases numerator increases more

d= 0.2 = _______effect size d= 0.5 = _______effect size d= 0.8 = _______effect size

small medium large

True or False The results of a hypothesis test can either indicate that there is enough evidence to reject Ho (and conclude the H1) or there is not enough evidence to reject Ho.

true

Rejecting H0 (null) when H0 is true is a _______ error.

type I

Not rejecting HO (null) when HO is false is_________. a. type I error b. correct decision c. type II error

type II error

What decision should be made if the test statistic is in the critical region? a. you can reject the null hypothesis b. you cannot reject the null hypothesis c. you can reject the alternative hypothesis

you can reject the null hypothesis

What factors listed below affect the power of the z statistic: M σ /√n Sample size (n) α

σ /√n Sample size (n) α

The denominator of the test statistic for the z test is________(σ /√n, σ /n). A decrease in this denominator _______(increases, decreases) the power of the z test, because this change _______(increases, decreases) the overall test statistic, making it more likely you will reject the null hypothesis. This denominator decreases when either the sample size (n) ________(increases, decreases) or the population standard deviation___________(increases, decreases).

σ /√n increase increase increases decreases