Method: Interaction

Methods: Diagnostics, Dummy Variable, Interaction, Regression,
Topics: Economics, Government, Consumer,
Datafile Name: Home Prices

From data maintained by the multiple listing agency in Albuquerque, the file contains prices of home resales along with descriptive data on the home, including square feet, age, number of certain features, custom built or not, and corner location or not. Another dummy variable is whether the home...

Methods: Nested Model, Interaction, Experimental Design,
Topics: Medical,
Datafile Name: Heart Valves

Artificial heart valves were tested in a mechanical apparatus which measured and controlled the pulse rate and the blood pressure of the heart. The purpose of the experiment was to determine the best valve type of the four studied. The maximum flow gradient (in mm Hg) is the dependent variable fo...

Methods: Regression, Interaction,
Topics: Food, Consumer,
Datafile Name: Beef Council Check-off

Average size of farm (SIZE) and percent of farms with sales of $100,000 or more dominate the regression of percent of farmers voting yes for the American Beef Council check-off (YES) on characteristics of farms and operators by counties in Montana. In fact, there is a strong interaction of these ...

Methods: ANCOVA, Distribution, Interaction, Transformation,
Topics: Economics,
Datafile Name: Billionaires 92

Fortune magazine publishes a list of the world's billionaires each year. The 1992 list includes 233 individuals. Their wealth, age, and geographic location (Asia, Europe, Middle East, United States, and Other) are reported.

The variable 'wealth' is right skewed, so the mean ...

Methods: Regression, Interaction, Time Series,
Topics: Economics, Education,
Datafile Name: Enrollment Forecast

These data were used by the Office of Institutional Research at the University of New Mexico to forecast fall undergraduate enrollment. Both the January unem- ployment rate and the June high school graduates for a year are known before students enroll in the university in the fall.

The ...

Methods: Regression, Interaction, Dummy Variable, ANOVA,
Topics: Consumer, Food,
Datafile Name: Taste Test Scores

Two-way analysis of variance with two levels of each classification can be easily handled by regression analysis with dummy (0,1) variables for the two levels. The example involves food taste scores in an experiment in which a coarse and fine screen for texture and a high and low liquid level wer...

Methods: Regression, Polynomial Regression, Residuals, Interaction,
Topics: Sports,
Datafile Name: Great Pitchers

The linear regression of hits, control, and clutch measures on the earned run averages (ERA) of leading baseball pitchers of the 1920-1950 era accounts for 96.7 percent of the variation on ERA's. However, a check of the residuals against the predictor variables finds a non-linearity with resp...

Methods: Regression, Dummy Variable, Interaction,
Topics: Consumer, Engineering,
Datafile Name: Nambeware Polishing Times

The average polishing times for 59 products are related in general to the sizes of the products as indicated by product diameter (or equivalent). However, dif- ferent types of products have special problems in polishing. For example, cas- seroles are deeper than ordinary plates and on that accoun...

Methods: Regression, Dummy Variable, Interaction, Transformation,
Topics: Consumer, Engineering,
Datafile Name: Nambeware Polishing Times

The relation between polishing time and product diameters as well as type of product (casserole, other) is one which is useful to the company for estimating the polishing time for new products which are designed or suggested for design and manufacture. A necessary regression assumption is that th...

Methods: Outlier, Regression, Residuals, Interaction, Dummy Variable,
Topics: Economics, Sports,
Datafile Name: Q-back and Team Salaries

The datafile contains 1991 season leading quarterback and total team salary
for football teams in the American Football Conference (AFC) and National
Football Conference (NFC) of the National Football League(NFL). Two poten-
tial influential observations (Steelers and Bears) ...

Methods: Dummy Variable, Diagnostics, Interaction, Outlier, Residuals, Transformation,
Topics: Economics, Education, Government,
Datafile Name: Teacher Pay by States

The scatter diagram below shows one potential influential observation, namely Alaska, which is an outlier in terms of spending per pupil. In addition, the question can be raised whether the level and slope of an appropriate regression line would be the same for the three regions of the country. S...

Methods: Regression, Interaction, Dummy Variable,
Topics: Economics, Government,
Datafile Name: Unions and State Labor Law

The dummy variables for presence of state bargaining laws covering public employees and presence of state right to work laws in the datafile provide an opportunity to examine a two-predictor regression involving dummy varia- bles. In this case there is interaction between the two dummy variables ...

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