(70 pts possible)
Module/Week 6’s assignment has two parts. The objective of your fifth Excel assignment is to learn to construct confidence intervals and conduct hypothesis tests in Excel based on data whose population parameters are known. You will also answer questions about your results. Part One involves constructing a confidence interval for the population mean based on sample data; Part Two involves testing a hypothesis about the same sample in comparison to the known population. First, be sure you view the presentation found in the Reading & Study folder in Module/Week 6. This presentation provides information and goes through the steps you will need to be familiar with in order to complete this assignment.
Research Question for Parts 1 and 2:A health psychologist wants to study overall student health on a university campus. One measure he decides to take is that of minutes exercised per week. Assume that we know from previous studies that the population mean for minutes of exercise per week for college students is μ = 100 with a standard deviation of σ = 25.
The health psychologist in question is particularly interested in the myth of the “Freshmen 15.” This myth claims that most freshmen gain weight during the first year of college, mostly due to bad eating habits and lack of exercise and sleep. He wonders if the Freshmen on his campus actually exercise less than the general population of college students. He randomly selects a sample of 50 Freshmen students and asks them how many minutes they exercise per week. The raw data collected by the health psychologist are in this module/week’s Data Set, entitled “Data Set 5”.
Part 1: Confidence Interval
1. Open the Excel file entitled “Data Set 5”. The file contains the following: a) raw data for the sample of 50 Freshmen; b) a results table for Part 1; c) Questions for Part 1; d) a results table for Part 2; and e) Questions for Part 2.
2. Construct a 95% Confidence Interval of the population mean of minutes exercised per week.
a. First, fill in cells with information given in the research question above (N and sigma). (4 pts)
b. In the appropriate cell in the table, compute the sample mean using the raw data given in column A. (Use the AVERAGE function.) (4 pts)
c. Determine the alpha level for this problem and type it in the appropriate cell. (4 pts)
d. As seen in this module/week’s presentation, use the CONFIDENCE function to compute the 95% confidence interval in the appropriate cell in the table. (4 pts)
e. Again as seen in the presentation, compute the lower and upper limits of the confidence interval in the appropriate cells.(4 pts)
3. Answer all five questions beneath the first table. Type answers directly into the Excel file as indicated. (Questions = 3 points each for total of 15 pts.)
Part 2: Hypothesis Test
1. State the null and alternative (research) hypothesis in symbolic form. The hypothesis should be written based on the following information from the research situation: “The health psychologist in question is particularly interested in the myth of the ‘Freshmen 15.’ This myth claims that most freshmen gain weight during the first year of college, mostly due to bad eating habits and lack of exercise and sleep. He wonders if the Freshmen on his campus actually exercise less than the general population of college students (which has a μ = 100 and σ = 25).” (Remember that your hypothesis should include evaluators such as =, <, > or a combination of these.) (2 pts)
2. Is your hypothesis directional or non-directional? Read the wording again in question 1 if you are unsure. The evaluators (=, <, >, etc.) you used in stating the hypotheses in question 1. above should also give you a clue. Fill in the cell with either “one-tailed” or “two-tailed” based on whether the alternative hypothesis is directional or not. Also, if you fill in “one-tailed”, answer the question to the right of the table concerning the direction of the tail. This decision will help you determine the critical values of your test statistics later, so think carefully! (2 pts)
3. Fill in the cells for N, μ, and σ which are already known. These will be used in formulas as shown in this week’s presentation. (2 pts)
4. In the appropriate cell in the table, compute the Standard Error of the Mean (σM) using the steps shown in this week’s presentation. (2 pts)
5. Fill in the sample mean (M), again using the AVERAGE function. (2 pts)
6. We are going to test our hypothesis at the .05 level of significance. Enter the alpha value in the appropriate cell. (2 pts)
7. Find the critical Z value for our test, based on the alpha level, using the NORMSINV function as shown in this module/week’s presentation. Remember to consider the direction(s) of your hypothesis when computing this Z value! (2 pts)
8. Compute the sample Z score using the steps gone over in this module/week’s presentation. (2 pts)
9. Fill in the critical p-value based on your alpha level. (2 pts)
10. Compute your sample’s p-value (based on your sample’s Z score) by using the NORMSDIST function as shown in this week’s presentation. (2 pts)
11. Answer all five questions underneath the second table directly in Data Set 5, after each question as indicated. (Questions = 3 points each for total of 15 pts.)
Save your work as “yourname_excel5.xls” and submit it by 11:59 p.m