Please do a good job

Week 4 Assignment

1. For each correlation coefficient below, calculate what proportion of variance is shared by the two correlated variables:

a. r = 0.25

b. r = 0.33

c. r = 0.90

d. r = 0.14

2. For each coefficient of determination below, calculate the value of the correlation coefficient:

a. r2 = 0.54

b. r2 = 0.13

c. r2 = 0.29

d. r2 = 0.07

3. Suppose a researcher regressed surgical patients’ length of stay (dependent variable) in the hospital on a scale of functional ability measured 24 hours after surgery. Given the following, solve for the value of the intercept constant and write out the full regression equation:

Mean length of stay = 6.5days; mean score on scale = 33; slope = -0.10

4. Using the regression equation calculated in Exercise 3, compute the predicted value of Y (length of hospital stay) for patients with the following functional ability scores:

a. X = 42

b. X = 68

c. X = 23

d. X = 10

5. Use the regression equation below for predicting graduate GPA for the three presented cases.

Y′ = -1.636 + 0.793(undergrad GPA) + 0.004(GREverbal) – 0.0009(GREquant)

+0.009(Motivation)

Subject undergrad GPA GREverbal GREquant Motivation

1 2.9 560 540 55

2 3.2 550 590 65

3 3.4 600 550 70

6. Using the following information for R2, k, and N, calculate the value of the F statistic for testing the overall regression equation and determine whether F is statistically significant at the 0.05 level:

a. R2 = 0.13, k = 5, N = 120

b. R2 = 0.53, k = 5, N = 30

c. R2 = 0.28, k = 4, N = 64

d. R2 = 0.14, k = 4, N = 64

7. According to the University of Chicago, as men age, their cholesterol level goes up. A new drug (XAB) is being tested to determine if it can lower cholesterol in aging males and at what dose. The data for the first test subject is below:

Dose (mg) 2 3 5 6 8 10

Cholesterol level (mg/dL) 310 124 201 110 52 20

a. Plot the data and include a regression line in StatCrunch. Copy and paste your graph into your Word document for full credit.

b. What is the correlation coefficient r and what does it mean in this case?

c. What is the coefficient of determination and what does it mean in this case?

d. Is there a statistically significant correlation between dose and cholesterol level in this case?

e. What is the predicted cholesterol level for a person taking a dose of 4 mg? What about if they are not taking the drug at all (0 mg)?

This IS NUMBER 8 QUESTION FROM THE LAST ASSIGNMENT #3

8. Below are three sets of expected frequencies for the four cells of 2 X 2 contingency tables. Identify which statistical procedure would be appropriate for each, using the most conservative approach.

a. 4 4 b. 35 35 c. 9 9

21 21 65 65 91 91

THE Options are

Yates’ Continuity Correction

Fisher’s Exact Test

Chi-Square test of Independence

We need to Use one of the options.

You need to choose one of these, to determine which statistically procedure is appropriate for each, using one of these TEST Listed above.

these are steps to follow.

For number 1 a,b and C, you are squaring the values, you will take correlation coefficient and square it to find the coefficient of determination , the R square. Then write down the values .

For number 2, you do it backward, take square root of the number to the correlation coefficient of determination .

Number 4 has 2 answers, solve for A first, use Regression equation , Do Algebra, then when you get A, you plug it in back into the Regression equation , create a new regression equation , then Use That to Solve NUMBER 4 Question.

For Number 5, do some Algebra, plug in the numbers. 3 Answers needed.

For 6, use this formulae F=R square of 2 divided by K OVER (1-R Squared 2)divided by N-K-1.

For number 7, the graph is scatter plot .