Question

1a)

Montarello and Martins (2005) found that fifth grade students completed more mathematics problems correctly when simple problems were mixed in with their regular math assignments. To further explore this phenomenon, suppose that a researcher selects a standardized mathematics achievement test that produces a normal distribution of scores with a mean of µ= 100 and a standard deviation of σ = 24. The researcher modifies the test by inserting a set of very easy problems among the standardized questions and gives the modified test to a sample of n = 36 students. If the average test score for the sample is M = 120, is this result sufficient to conclude that inserting the easy questions improves student performance? Use a one-tailed test with α = .05.

The null hypothesis in words is

Group of answer choices

Inserting the easy questions decreases student performance on the achievement test

Inserting the easy questions does not affect student performance on the achievement test

Inserting the easy questions does not improve student performance on the achievement test

Inserting the easy questions improves student performance on the achievement test

b)The alternative hypothesis in symbols is

c)The critical z value is

d)The z-score statistic is:

e)

Your decision is

Group of answer choices

Reject the null hypothesis because the z-score statistic is greater than the critical z value

Reject the null hypothesis because the z-score statistic is not greater than the critical z value

Fail to reject the null hypothesis because the z-score statistic is greater than the critical z value

Fail to reject the null hypothesis because the z-score statistic is not greater than the critical z value

1b)

Suppose that over the past 30 years during any given week of the major-league season, an average of µ = 12 players are hit by wild pitches. Assume that the distribution is normal with a standard deviation of σ =3. For a sample of n = 4 weeks, in which the daily temperature was extremely hot, the weekly average of hit-by- pitch players was M = 16.

Are players more likely to get hit by pitches during hot weeks? Use a one-tailed test with α = .01.

The alternative hypotheses in words is:

Group of answer choices

The number of hit-by-pitch players during hot weather remains the same

The number of hit-by-pitch players during hot weather significantly changes

There is a significant increase in the number of hit-by-pitch players during hot weather.

There is not a significant increase in the number of hit-by-pitch players during hot weather.

a)The null hypothesis in symbols is:

b)The critical z value is

c)The z-score statistic is:

d)

Your decision is

Group of answer choices

Reject the null hypothesis and conclude that that there is a significant increase in the number of hit-by-pitch players during hot weather

Reject the null hypothesis and conclude that that there is not a significant increase in the number of hit-by-pitch players during hot weather

Fail to reject the null hypothesis and conclude that that there is a significant increase in the number of hit-by-pitch players during hot weather

Fail to reject the null hypothesis and conclude that that there is not a significant increase in the number of hit-by-pitch players during hot weather

e)

Compute Cohen’s d to estimate the size of the effect.

Cohen's d is:

f)Report the results in APA

1c)

A researcher conducts a hypothesis test to evaluate the effect of a treatment that is expected to increase scores. The hypothesis test produces a z-score statistic of z= 1.23 , if the researcher is using a one-tailed test, what is the correct statistical decision?

Group of answer choices

Reject the null hypothesis with α = .05, but not with α = .01

Reject the null hypothesis with either α = .05 or α = .01

Fail to reject the null hypothesis with either α = .05 or α = .01

cannot answer without additional information

Answer 1