groebner business statistic 8ed ch15 xl 2007 tutorial

Guide to Using Excel 2007 For Basic

Statistical Applications

To Accompany

Business Statistics: A Decision Making

Approach, 8th Ed.

Chapter 15:

Multiple Regression and Model Building

By

Groebner, Shannon, Fry, & SmithPrentice-Hall Publishing Company

Copyright, 2011

Chapter 15 Excel Examples

Multiple Regression

First City Real Estate

Multiple Regression –Dummy Variable


Curvilinear Regression

Ashley Investment Services

Interaction Effects


More Examples

Chapter 15 Excel Examples

Residual Analysis


Multiple Regression –First City Real Estate

Issue: First City management wishes to build a

model that can be used to predict sales prices

for residential property.

Objective: Use Excel 2007 to build a multiple

regression model relating sales price to a set of

measurable variables.

Data file is FirstCity.xls

Multiple Regression – First City Real Estate

•Open the file FirstCity.xls, Sheet Homes-Sample 1

•Select the Data Tab

•Select Data Analysis

•Select Correlation

•OK


•Input Range: A1:G320

•Grouped by: Columns

•New Worksheet Ply: corr-1

•OK


This cell shows the correlation, 0.7477, between Price and Square Feet


Return to Homes-Sample 1

•Select the Data tab


•Select Regression

•OK


•Input Y Range: A1:A320

•Input X Range: B1:F320

•Select labels

•New Worksheet Ply: regress-1

•OK


Excel produces the Regression Model


To determine if multicollinearity is a problem:

•Select the Add-Ins tab

•Select PHStat


•Select Multiple Regression


•Y variable … : A1:A320

•X variable … : B1:F320

•Select First Cells in both …

•Select Regression Statistics …

•Select ANOVA and …

•Select Variance Inflation …

•OK


PHStat will find Variance Inflation Factors for all independent variables. This slide shows the VIF for Garage # and all other X variables. Click on the sheet tabs X4,X3,X2,X1 to see the VIF for the other variables.

Issue: First City managers wish to improve the

model by adding a location variable for the area.

Objective: Use Excel 2007 to improve a regression

model by adding a dummy variable for the area

either foothills or flatland.

Data file is First City.xls

Multiple Regression - Dummy

Variable -First City Real Estate

Multiple Regression- Dummy Variable –


•Select the Home-Sample 2 sheet

•Select the Add-In tab

•Select PHStat


•Select Multiple Regression



•Cut Bedrooms and Bathrooms columns and paste in cell G1. Delete columns C and D so that all data is in connected columns

•Select Data tab


•Input Y Range: A1 – A320

•Input X Range B1-E320

•Select Labels

•New Worksheet: Regress-2

•OK



All variables are significant and have the expected sign

Curvilinear Relationships -


Issue: The director of personnel is trying to determine

whether there is a relationship between employee

burnout and time spent socializing with co-workers.

Objective: Use Excel 2007 to determine whether the

relationship between the two measures is statistically

significant.

Data file is Ashley.xls

Curvilinear Relationships – Ashley Investment Services

Open the file Ashley.xls


•Select A1:B21

•Select the Insert Tab

•Select Scatter Plot

•Select the Scatter Plot desired


•Y Range A1:A21

•X Range B1:B21

•Labels

•New Worksheet Ply: Ashley-1

•OK


To develop a nonlinear model, return to the data file. Create a new variable Socialization Squared





•OK


• Input Y Range: A1:A21• Input X Range: B1:C21• Select Labels• New Worksheet Ply: Ashley-2


The output shows the R Square value and the Regression Coefficients.

Interaction Effects -


Issue: The director of personnel is trying to determine

whether the model can be improved by separating

observations between those taken from men and

women.

Objective: Use Excel 2007 to determine whether the

relationship between the measures can be improved.

Data file is Ashley-2.xls

Interaction Effects – Ashley Investment Services

•Open file Ashley-2.xls

•Insert a new column C as (Socialization Squared) which is Column B squared

•Add Column E as Columns B * D

•Add Column F as Columns C * D


Using The Insert tab and Chart tools set up a Scatter Plot for one gender


Add the second gender

Add exponential trend line for male and female


The regression for the curvilinear model.

Issue: The company is interested in analyzing the

residuals of the regression model to determine

whether the assumptions of multiple regression are

satisfied.

Objective: Use Excel 2007 to analyze residuals from

a regression model.

Data file is First City-3.xls

Residual Analysis -


Residual Analysis – First City Real Estate

Open the file FirstCity3.xls

Since Excel requires independent variables to be in adjacent columns – cut and paste these columns.

We will be using:

•Price

•Sq. Feet

•Bedrooms

•Garage #

•Log of Lot Size

•Note: I will swap Lot Size and Log Lot Size to simplify the operation


•Select the Data tab•Select Data Analysis•Select Regression•OK


Define the range for X and Y variables.Excel gives several options for Residual Analysis but does not have as complete a set as Minitab


This is the Residual Plot for Square Feet


While Excel will not automatically generate a histogram of the standardized residuals , one can be created.


Define Bin values for the Histogram


•Select the Data tab•Select Data Analysis•Select Histogram•On the Histogram Chart identify the data and bins•Select Chart output

groebner business statistic 8ed ch15 xl 2007 tutorial

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