xmp13.09 {Devore6} | R Documentation

## data from Example 13.9

### Description

The `xmp13.09` data frame has 8 rows and 2 columns of data on cure temperature and ultimate sheer strength of rubber compounds.

### Format

This data frame contains the following columns:

tempture
  cure temperature (degrees Fahrenheit).
strength
  ultimate sheer strength (psi)

### Source

Devore, J. L. (2003) Probability and Statistics for Engineering and the Sciences (6th ed), Duxbury

(1971), "A method for improving the accuracy of polynomial regression analysis", J. Quality Technology, 149–155.

### Examples

    data(xmp13.09)
    plot(strength ~ tempture, data = xmp13.09)
    fm1 <- lm(strength ~ tempture + I(tempture^2), data = xmp13.09)
    summary(fm1)
    xmp13.09$Tcentered <- scale(xmp13.09$tempture, scale = FALSE)
    fm2 <- lm(strength ~ Tcentered + I(Tcentered^2), data = xmp13.09)
    summary(fm2)
    ## another approach using orthogonal polynomials
    fm3 <- lm(strength ~ poly(tempture, 2), data = xmp13.09)
    summary(fm3)

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