Question

Fro the give information, n=25, M=7.29, u=7.52, o=0.60, and a=0.05 a. can the researcher conclude that reviews during hot weather are significantly lower than the general population average? use a one-tailed test with a=0.05 b. Compute Cohen's d to measure effect size for this unit. c. Write a sentence demonstrating how the outcome of the hypothesis test and the measure of effect size would appear in a research report.

Answer 1

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Answer:

a)

The null hypothesis states that there is no effect of the treatment and alternative hypothesis states opposite of null hypothesis. As given in the question that population mean is 7.52 and one tailed test is used, so the null hypothesis and alternative hypothesis for this question are:

Rejection rule:

The hypothesis is rejected when the calculated value of z is greater than the critical value of z in the given level of significance.

Conclusion:

The calculated z value is greater than the critical value of z.

The null hypothesis is rejected.

The researcher concludes that reviews during hot weather are significantly lower than the general population In other words null hypothesis is rejected and population mean is less than 7.52.

b)

Samples mean (M) is given as 7.29, population mean is given as 7.52, standard deviation is given as 0.60, alpha level is given as 0.05 and sample size is given as 25.

Justification:

The Cohen’s d value is calculated as:

c)

The null hypothesis is rejected for the test and the measure of effect size (Cohen’s d) indicate that the treatment results in change in the mean by less than half of the standard deviation ( d=−0.383)

Justification:

As the calculated value is −1.92−1.92 and critical value is −1.65−1.65, so the calculated value is greater than critical value. Also p value is less than maximum of alpha level as alpha level is given, so p value is: p<0.05

It means the z-score lies under critical region, so the null hypothesis is rejected. In other words, the researcher concludes that reviews during hot weather are significantly lower than the general population. The measure of effect size (Cohen’s d) indicates that the treatment results in change in the mean by less than half of the standard deviation ( d=−0.383). In other words treatment effect appears to have decreased the reviews by 0.23 points, which is equal to less than half of the standard deviation.