A researcher selects a sample from a population with µ = 30 and uses the sample to evaluate the effect of a treatment. After treatment, the sample has a mean of M = 32 and a variance of s2 = 6. If Cohen’s d is used to measure the size of the treatment effect, which of the following would have no effect on the value of Cohen’s d?   Group of answer choices an increased sample size an increased sample mean an increase sample variance Each of these of these aspects will influence the value of Cohen’s d.

A medical researcher wants to test whether the mean cholesterol levels are the same for 3 treatment groups of subjects (with 18 total randomly selected subjects): those who take a new medication, those who follow a diet, and those who make no changes to medication or diet. They plan to use a 5% level of significance for their decision. Below is a partial Analysis of Variance table. Use it to answer the following questions deg of freedom Sum of Squares Mean Square F statistic Treatment Group 3.121 1.5607 Error 1.517 0.1011 Total 17 What are the degrees of freedom for the treatment groups? What are the degrees of freedom for the error? What is the F-statistic for this data (3 decimal places)

A researcher was interested in knowing if mean BMI was different between males and females. He obtained the following test results. Choose the correct interpretation of the results: F test p value = 0.03 Two sample t test, assume equal variance = 0.02 Two sample t test, assume unequal variance = 0.06 Mean BMI is higher in males than females. None Mean BMI is not significantly different between males and females. Mean BMI is significantly different between males and females.

A sample of 100 scores has a mean of 58, a variance of 160, and an estimated standard error of 4. Which of these values is guaranteed to increase if the sample size is decreased to 10? a. none of these is likely to be changed very much by decreasing n.   b. the value of the variance   c. the value of the mean   d. the value of the standard error

A researcher was interested in knowing if mean BMI was different between males and females. He obtained the following test results. Choose the correct interpretation of the results: F test p value = 0.30 Two sample t test, assume equal variance = 0.02 Two sample t test, assume unequal variance = 0.61 Mean BMI is not significantly different between males and females. None Mean BMI is higher in males than females. Mean BMI is significantly different between males and females.

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 7.9 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 24 samples is 8.1 ppm with a variance of 0.25. Does the data support the claim at the 0.1 level? Assume the population distribution is approximately normal. Step 5 of 5:  Make the decision to reject or fail to reject the null hypothesis.

Consider the following data: 7 8 P(X = x) 0.2 0.2 0.2 0.2 0.2 %3D Step 2 of 5: Find the variance. Round your answer to one decimal place. 5.

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 4.6 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 14 samples is 4.9 ppm with a variance of 1.2 Does the data support the claim at the 0.01 level? Assume the population distribution is approximately normal. Step 2 of 5 :   Find the value of the test statistic. Round your answer to three decimal places.

What is the value of n (the number of observations)? What is the value of Se (standard error for the model) (2 decimals)? What is the average of the x variable (2 decimals)? What is the variance of the x variable (1 decimal)?

You are testing the claim that having lights on at night increases weight gain (abstract). A sample of 10 mice lived in an environment with bright light on all of the time and 8 mice who lived in an environment with a normal light/dark cycle is given below. Test the claim using a 2% level of significance. Assume the population variances are unequal and that the weight changes are normally distributed. Give answers to 3 decimal places. Data available at StatKey, choose Mice Wgt Gain-2e data set Light (1) 1.71 4.67 4.99 5.33 5.43 6.94 7.15 9.17 10.26 11.67 What are the correct hypotheses? Note this may view better in full screen mode. Select the correct symbols in the order they appear in the problem. Ho: ₁ Test Statistic = Dark (₂) 2.27 2.53 2.83 4 4.21 4.6 5.95 6.52 Ha: ₁ Based on the hypotheses, find the following: p-value = = V Select an answer ✓ Select an answer (Hint: difference in means from H₂) The correct decision is to fail to reject the null hypothesis The correct summary…