A. Researchers examined the relationship between cola consumption and bone loss after fifty. One thousand women were randomly sampled, everyone's cola consumption was recorded over a two month period of time, and bone density measures were also recorded. Researchers found that the more cola consumed, the lower the level of bone density. They concluded that cola consumption leads to loss of bone density.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity.

B. Researchers examined differences in attitudes towards drinking between high school freshman and high school seniors. 400 students completed questionnaires that included information about drinking attitudes. The researchers found that older students maintained more liberal attitudes towards drinking than younger students. The researchers concluded that attitudes towards drinking and alcohol become more liberal with age.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity

Dr. Jones is interested in the effects of caffeine on performance. She randomly splits her statistics class of 15 students into three groups. Prior to the final exam, she has one group take no caffeine prior to taking the exam, students in another group take 100 mg of caffeine, and students in the third group take 200 mg of caffeine. She records the grades in each condition.

a. State the null hypothesis.

b. Identify the appropriate statistical test

c. Calculate the appropriate test statistic. Make sure to report the degrees of freedom for the statistical test (if appropriate). You must show your work to receive full credit.

d. State your conclusions (use a two-tailed test with  = .05 for all tests).

e. Compute an effect size

Students enrolled in an introductory statistics course at a university were asked to take a survey that indicated whether the student’s learning style was more visual or verbal. Each student received a numerical score ranging from -11 to +11. Negative scores indicated a visual learner, and positive scores indicated a verbal learner. The closer the score was to -11 or +11, the stronger the student’s inclination toward that learning style. A score of 0 would indicate neutrality between visual or verbal learning. For the 36 students who took the survey, the mean score was -2.744, and the standard deviation was 4.988.

1. State the null and alternative hypotheses for testing whether the mean score (among all students at this university) differs from 0.

2. Calculate the value of the t-test statistic for the hypotheses stated in question 1.

3. Determine the p-value of the test as accurately as possible.

4. Summarize the conclusion that you would draw from this test.

5. Comment on whether the technical conditions of this t-test are satisfied.

The Studious Frog provides study support and tutoring services for high school students during their finals. All services require cash payment in advance. Studious Frog provides an Finals Prep course for $480, as well as a Post- Finals Review course for $120. The finals prep course takes place before the students have their final tests, and the finals review course takes place after finals are complete. During December 2022, The Studious Frog offered a promotional package where students could purchase a package for both courses for the price of $580. On December 10, a total of 100 promotional packages were sold for cash, and on the same day, the Finals Prep course was provided. On December 31, the Post-Finals Review course was provided.

Using the five-step model for revenue recognition under the contract-based approach, record all necessary transactions related to the promotional package sold by The Studious Frog Services

How Laude? Many educational institutions award three levels of Latin honors often based on GPA. These are cumlaude (with high praise), magnacum laude (with great praise), and summa cumlaude (with highest praise). Requirements vary from school to school. Suppose the GPAs at State College are normally distributed with a mean of 2.75 and standard deviation of 0.47.

(a) Suppose State College awards the top 2% of students (based on GPA) with the summa cumlaude honor. What GPA gets you this honor? Round your answer to 2 decimal places.
????? GPA or higher

(b) Suppose State College awards the top 10% of students (based on GPA) with the magna cumlaude honor. What GPA gets you this honor? Round your answer to 2 decimal places.
???? GPA or higher

(c) Suppose State College awards the top 20% of students (based on GPA) with the cumlaude honor. What GPA gets you this honor? Round your answer to 2 decimal places.
???? GPA or higher

2.2. Indicate which test (paired samples (ie dependent) t-test, independent two samples t-test, one-sample t-test, independent samples z-test) is most appropriate for the following situations :

A. Comparison of weight gain of two groups of 18 cows where one group was raised following standard practices and the other group was raised following “organic” standards.

B. Comparison of scores on a fitness test of Olympic-class distance runners (n=20) with the national average score of people of a similar age range (22-31 years).

C. Comparison of speed of texting on a smart phone of 20 teenaged students compared to one of their parents.

D. Comparison of speed at texting of 24 Trent students using the hand they write with versus their other hand.

E. Comparison of body weights of 50 Trent students who identified themselves in a survey as “normally athletic”. Weights were recorded just before and three months into the Covid-19 lockdown

Dr. Paddock is a counseling psychologist who is interested in decreasing adjustment issues in first-year college students. She is curious if having students create collages of their first few weeks of school and then mailing them home will help students feel they have integrated their new life with their old and, as a result, will help them feel less homesick. She samples a group of 100 incoming college freshmen at her university and measures how homesick they are during the first week of school. During Week 4 of school, she has them make the collage and send it home. During Week 7 of school, she measures their homesickness again. She notices a significant reduction in the amount of homesickness from the pretest to the posttest and concludes that her treatment is effective.

Name two threats to internal validity that are likely to be present in Dr. Paddock’s study, given her particular design. What other explanation do these threats provide for the results found by Dr. Paddock?

Students enrolled in an introductory statistics course at a university were asked to take a survey that indicated whether the student’s learning style was more visual or verbal. Each student received a numerical score ranging from -11 to +11. Negative scores indicated a visual learner, and positive scores indicated a verbal learner. The closer the score was to -11 or +11, the stronger the student’s inclination toward that learning style. A score of 0 would indicate neutrality between visual or verbal learning.  For the 39 students who took the survey, the mean score was -2.744, and the standard deviation was 4.988.

A. State the null and alternative hypotheses for testing whether the mean score (among all students at this university) differs from 0.

B. Calculate the value of the t-test statistic for the hypotheses stated in question 1.

C. Determine the p-value of the test as accurately as possible.

D. Summarize the conclusion that you would draw from this test.

E. Comment on whether the technical conditions of this t-test are satisfied.

SPSS NEEDED Person is interested in comparing the success of two different mnemonics (memorization methods) on performance in a memory task. He assigns students to two groups, one which learns and uses a language-based rhyming memory technique, and one which learns and uses a visual “method of loci” spatial memory technique. He then administers a memory task to each group of students. The students are scored based on the percentage of correct answers.

Using this table, enter the data into a new SPSS data file and run an independent-samples t test to test the claim that there is a difference in the percentage of correct answers between the two groups.

Part A - Paste SPSS data

Part B - Write an APA-style Results section based on your analysis. Include your boxplot as an APA-style figure

Students enrolled in an introductory statistics course at a university were asked to take a survey that indicated whether the student’s learning style was more visual or verbal. Each student received a numerical score ranging from -11 to +11. Negative scores indicated a visual learner, and positive scores indicated a verbal learner. The closer the score was to -11 or +11, the stronger the student’s inclination toward that learning style. A score of 0 would indicate neutrality between visual or verbal learning.  For the 39 students who took the survey, the mean score was -2.744, and the standard deviation was 4.988.

A. State the null and alternative hypotheses for testing whether the mean score (among all students at this university) differs from 0.

B. Calculate the value of the t-test statistic for the hypotheses stated in question 1.

C. Determine the p-value of the test as accurately as possible.

D. Summarize the conclusion that you would draw from this test.

E. Comment on whether the technical conditions of this t-test are satisfied.