Question

NAME Statistics in Psychological Research Homework 4 Your homework must consist entirely of your own work. You will need to show your work for calculations in order to receive full credit. Showing your calculations will also allow us to award partial credit due to minor calculation errors. PLEASE BE SURE TO TYPE THE MAJOR STEPS FOR FULL CREDIT AND ROUND TO 2 DECIMAL PLACES.

1. State the null and research hypothesis for each research scenario. [3pts, 1pts each]

a. A researcher is interested in studying the use of antibacterial products and the dryness of people’s skin. He thinks these products might alter the moisture in skin compared to other products that are not antibacterial.

b. A student wonders if grades in a class are any way related to where a student sits in the classroom. In particular, do students who sit in the front row get better grades on average, than the general population of students?

c. Cell phones are everywhere and we are now available by phone almost all of the time. Does this translate into a change in the nature or closeness of our long distance relationships?

2. A psychologist is interested in how the game “Words with Friends” affects the vocabulary skills of 8th graders in the United States. The psychologist conducts an experiment in which a random sample of n = 25 8th grade students are required to play “Words with Friends” for 1 hour per day for an entire week. At the end of the experiment, the students are given a standardized vocabulary test which has a mean of μ = 60, and standard deviation of σ = 10. The test is scored such that lower scores indicate a better vocabulary. The sample of 25 8th graders had a mean score of M = 55. [6pts total]

a. Is there a significant difference in average vocabulary score for the sample of 8th grade students when compared to the population? Conduct the six steps of hypothesis testing to find your answer and use α = .01.

3. Suppose the average amount of chocolate chips in a jumbo chocolate chip cookie is, μ = 35 with a standard deviation of σ =3.5. You bake a batch of jumbo chocolate chip cookies and find that your batch of 8 cookies has an average of 39 chips. [4pts/ 2pts each]

a. Using a 95% confidence interval, test the hypothesis that your average number of chocolate chips in your jumbo chocolate chip cookies significantly differs from the population average. Be sure to use the z table to find the correct critical value. Questions continue on next page.

b. Compute the effect size for the above study.

4. What is the relationship between power and type II error? [2pts] 5. Describe what happens to the power of a study for each condition. Please provide a sentence or for each explaining why power changes. [5pts/ 1pt each]

a. The sample size of a study is increased.

b. A researcher changes their type I error rate from α = .05 to α = .01.

c. The effect size of the study is increased by exaggerating levels of the IV. d. A researcher increases the standard deviation in their sample (i.e., their sample has more variability) e. A researcher changes their hypothesis test from one-tailed to two-tailed.

Answer 1

1. State the null and research hypothesis for each research scenario. [3pts, 1pts each]

a. A researcher is interested in studying the use of antibacterial products and the dryness of people’s skin. He thinks these products might alter the moisture in skin compared to other products that are not antibacterial.

The hypothesis being tested is:

H0: There is no relationship between the use of antibacterial products and the dryness of people’s skin

Ha: There is a relationship between the use of antibacterial products and the dryness of people’s skin

b. A student wonders if grades in a class are any way related to where a student sits in the classroom. In particular, do students who sit in the front row get better grades on average, than the general population of students?

The hypothesis being tested is:

H0: Students who sit in the front row get the same grades on average, as the general population of students

Ha: Students who sit in the front row get better grades on average, than the general population of students

c. Cell phones are everywhere and we are now available by phone almost all of the time. Does this translate into a change in the nature or closeness of our long distance relationships?

The hypothesis being tested is:

H0: µ1 = µ2

H1: µ1 ≠ µ2

As per the Chegg answering guide, we have the option to answer only the first question in case of multiple questions. If you want to get the answers for the rest of the parts, please post the question in a new post.

Thank you! :)