Within-group variability reflects a. random, individual differences b. error variance c. pooled variance d. the effect of the independent variable

Why is it important to report both a measure of central tendency and variability to describe a set of scores? Group of answer choices Sets of data with different central tendencies may have different patterns of variability. Sets of data with the same central tendency may have the same patterns of variability. Sets of data with the same variability may have different patterns of central tendency. Sets of data with the same central tendency may have different patterns of variability.

A one-way Analysis of Variance (ANOVA) was used to examine whether students’ scores on a standardized test is a function of the teaching method they received (either lecture only, hands-on learning only, or both together). The ANOVA was significant. Run post hoc tests (by hand!) to determine which pairs of the mean are significantly different. Do the math for each and then explain in what way are they different. Method N Mean SD   Source df SS MS F Lecture Only 15 82.8 9.59   Between 2 736.53 368.27 5.34 Hands-On Only 15 88.53 8.73   Within 42 2895.47 68.94   Both 15 92.67 6.22   Total 44 3632     Total 45 88

Suppose a researcher wants to determine if the proportion of students who graduate college in four years is different between those attending public universities compared to those attending private universities. Which method should the researcher use? Chi-square Goodness of Fit test Two-proportions test One-proportions test Analysis of Variance Two-sample t-test

A manager believes that the variance of output on the second shift is greater than the variance on the day shift. The following data are collected:   50 samples on the day shift; variance = 500 40 samples on the second shift; variance = 900 Set up hypotheses Perform a test and state your conclusions.

Researchers want to know if a tutoring program affects students’ ACT scores. They used a sample of twenty students and tested them before and after the tutoring program. Use Excel to perform a dependent sample t-test to determine whether the difference between the mean pretest score and the mean posttest score is significantly different. Assume unequal variance.   Subject Pretest Posttest 1 21 25 2 30 33 3 25 26 4 28 31 5 31 34 6 16 16 7 19 21 8 21 24 9 26 27 10 34 34 11 22 23 12 18 24 13 14 17 14 19 23 15 24 25 16 33 30 17 25 27 18 26 26 19 22 24 20 19 18

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 is the critical value of F we would compare this to (see F-table) [ Select ] What is our decision v [ Select ] More information is needed Do not reject the null hypothesis because our f-statistic is smaller than the critical f Reject the null hypothesis because our f-statistic is greater than the critical f Reject the null hypothesis because our f-statistic is smaller than the critical f Do not reject the null hypothesis because our f-statistic is…

Suppose the variance of X is 14. What is the variance of .47X?

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)

We are interested in determining whether or not the variances of the sales at two music stores (A and B) are equal. A sample of 16 days of sales at store A has a sample variance of 20 while a sample of 26 days of sales from store B has a sample variance of 30. The test statistic is (A) 1.50 (B) 1.69 (C) 2.25 (D) 2.50