AAA Co. operates distribution centers in the Midwest. Three of their centers were
recently audited to determine if they are in compliance with company standard billing
procedures. According to the auditing firm, a billing had an equal probability of being
from each of the three centers. A random sample of the audited billings had the
following distribution:
State the null hypothesis that states the expectations of the auditors.
The HR manager of a major office supply chain is interested in determining whether
employee educational level affects knowledge of their job. An exam was given to 120
employees. The results are below:
For each column total, calculate the corresponding percentage.
A human resource manager is interested in whether absences occur during the week
with equal frequency. The manager took a random sample of 100 absences and created
the following table:
Calculate the expected absences for all 5 days.
Below is a partial multiple regression ANOVA table.
Calculate the explained variation.
Consider the randomized block design with 4 blocks and 3 treatments given above.
What is the treatment sum of squares?
Consider the randomized block design with 4 blocks and 3 treatments given above.
What is the mean square error?
A data set with 7 observations yielded the following. Use the simple linear regression
model.
SSE = 1.117
Determine the 95 percent confidence interval for the average value of Y when x = 3.25.
A local tire dealer wants to predict the number of tires sold each month. He believes
that the number of tires sold is a linear function of the amount of money invested in
advertising. He randomly selects 6 months of data consisting of tire sales (in thousands
of tires) and advertising expenditures (in thousands of dollars). Based on the data set
with 6 observations, the simple linear regression model yielded the following results.
Determine the value of the estimated y-intercept.
A regression model was applied to a data set with 8 time-ordered observations. The
residuals for these observations are given below.
Calculate the Durbin-Watson statistic (d).
Consider the following partial computer output from a simple linear regression analysis.
Analysis of Variance
What is the unexplained variance?
Consider the randomized block design with 4 blocks and 3 treatments given above.
What is the value of the F statistic for blocks?
What is the degrees of freedom treatment (between-group variation) of a completely
randomized design (one-way) ANOVA test with 4 groups and 15 observations per each
group?
Below is a partial multiple regression computer output based on a quadratic regression
model.
Calculate R2.
Looking at four different diets, a researcher randomly assigned 20 equally overweight
women into each of the four diets. What are the degrees of freedom for the individual
confidence intervals?
A member of the state legislature has expressed concern about the differences in the
mathematics test scores of high school freshmen across the state. She asks her research
assistant to conduct a study to investigate what factors could account for the
differences. The research assistant looks at a random sample of school districts across
the state and uses the factors of percentage of mathematics teachers in each district with
a degree in mathematics, the average age of mathematics teachers, and the average
salary of mathematics teachers.
Test the overall usefulness of the model at α = .01. Calculate F and make your decision.