R: US Car Price Data

carprice

R Documentation

US Car Price Data

Description

U.S. data extracted from Cars93, a data frame in the MASS package.

Usage

carprice

Format

This data frame contains the following columns:

Type: Type of car, e.g. Sporty, Van, Compact
Min.Price: Price for a basic model
Price: Price for a mid-range model
Max.Price: Price for a ‘premium’ model
Range.Price: Difference between Max.Price and Min.Price
RoughRange: Rough.Range plus some N(0,.0001) noise
gpm100: The number of gallons required to travel 100 miles
MPG.city: Average number of miles per gallon for city driving
MPG.highway: Average number of miles per gallon for highway driving

Source

MASS package

References

Venables, W.N.\ and Ripley, B.D., 4th edn 2002. Modern Applied Statistics with S. Springer, New York.

See also ‘R’ Complements to Modern Applied Statistics with S-Plus, available from http://www.stats.ox.ac.uk/pub/MASS3/

Examples

 
print("Multicollinearity - Example 6.8")
pairs(carprice[,-c(1,8,9)])

carprice1.lm <- lm(gpm100 ~ Type+Min.Price+Price+Max.Price+Range.Price,
    data=carprice)
round(summary(carprice1.lm)$coef,3)
pause()

alias(carprice1.lm)
pause()

carprice2.lm <- lm(gpm100 ~ Type+Min.Price+Price+Max.Price+RoughRange, data=carprice)
round(summary(carprice2.lm)$coef, 2)
pause()

carprice.lm <- lm(gpm100 ~ Type + Price, data = carprice)
round(summary(carprice.lm)$coef,4)  
pause()

summary(carprice1.lm)$sigma   # residual standard error when fitting all 3 price variables
pause()

summary(carprice.lm)$sigma    # residual standard error when only price is used
pause()

vif(lm(gpm100 ~ Price, data=carprice)) # Baseline Price
pause()

vif(carprice1.lm)    # includes Min.Price, Price & Max.Price
pause()

vif(carprice2.lm)    # includes Min.Price, Price, Max.Price & RoughRange
pause()

vif(carprice.lm)     # Price alone