# Data file

## Introduction

Your instructor will provide you with a data file that includes data on five variables:

SALES represents the number of sales made this week.

CALLS represents the number of sales calls made this week.

TIME represents the average time per call this week.

YEARS represents years of experience in the call center.

TYPE represents the type of training the employee received.

## Part B: Hypothesis Testing and Confidence Intervals

Complete the following four hypotheses, using α = 0.05 for each. The week 5 spreadsheet can be used in these analyses.

1. Mean sales per week exceed 42.5 per salesperson

2. Proportion receiving online training is less than 55%

3 Mean calls made among those with no training is at least 145

4. Mean time per call is 14.7 minutes

Using the same data set from part A, perform the hypothesis test for each speculation in order to see if there is evidence to support the manager’s belief. Use the Eight Steps of a Test of Hypothesis from Section 9.1 of your text book as a guide. You can use either the p-value or the critical values to draw conclusions. Be sure to explain your conclusion and interpret that to the claim in simple terms

Compute 99% confidence intervals for the variables used in each hypothesis test, and interpret these intervals.

Write a report about the results, distilling down the results in a way that would be understandable to someone who does not know statistics. Clear explanations and interpretations are critical.

All DeVry University policies are in effect, including the plagiarism policy.

Project Part B report is due by the end of Week 6.

Project Part B is worth 100 total points. See grading rubric below.

#### Format for report:

Summary Report (about one paragraph on each of the four speculations)

Appendix with the calculations of the Eight Elements of a Test of Hypothesis, the p-values, and the confidence intervals. Include the Excel formulas or spreadsheet screen shots used in the calculations.

## Part C: Final Project: Regression and Correlation Analysis

Use the dependent variable (labeled Y) and one of the independent variables (labeled X1, X2, and X3) in the data file. Select and use one independent variable throughout this analysis. Use Excel to perform the regression and correlation analysis to answer the following. The week 6 spreadsheet can be helpful in this work.

Generate a scatterplot for the specified dependent variable (Y) and the selected independent variable (X), including the graph of the “best fit” line. Interpret.

Determine the equation of the “best fit” line, which describes the relationship between the dependent variable and the selected independent variable.

Determine the correlation coefficient. Interpret.

Determine the coefficient of determination. Interpret.

Test the utility of this regression model by completing a hypothesis test of β=0 using α=0.10. Interpret results, including the p-value.

Based on the findings in steps 1-5, analyze the ability of the independent variable to predict the dependent variable.

Compute the confidence interval for β, using a 95% confidence level. Interpret this interval.

Compute the 99% confidence interval for the dependent variable, for a selected value of the independent variable. Each student can choose a value to use for the independent variable (use same value in the next step). Interpret this interval.

Using the same chosen value for part (8), estimate the 99% prediction interval for the dependent variable. Interpret this interval.

What can be said about the value of the dependent variable for values of the independent variable that are outside the range of the sample values? Explain.

Describe a business decision that could be made based on the results of this analysis. In other words, how might the business operations change based on these statistical results.

All DeVry University policies are in effect, including the plagiarism policy.

Final Project report is due by the end of Week 7.

Final Project is worth 130 total points. See grading rubric below.

Summarize your results from Steps 1-11 in a 3-page report. The report should explain and interpret the results in ways that are understandable to someone who does not know statistics.

Submission: The Word document, summary report should be submitted for questions 1-11. The Excel output can be included as an appendix, if needed.

#### Format for report:

Summary Report

Steps 1-11 addressed with appropriate output, graphs and interpretations. Be sure to number each step 1-11.