House Insulation: Whiteside's Data

SUMMARY:

Mr Derek Whiteside of the UK Building Research Station recorded the weekly gas consumption and average external temperature at his own house in south-east England for two heating seasons, one of 26 weeks before, and one of 30 weeks after cavity-wall insulation was installed. The object of the exercise was to assess the effect of the insulation on gas consumption.

DATA DESCRIPTION:

The whiteside data frame has 56 rows and 3 columns.:

ARGUMENTS:

Insul
A factor, before or after insulation.
Temp
Purportedly the average outside temperature in degrees Celsius. (These values is far too low for any 56-week period in the 1960s in South-East England. It might be the weekly average of daily minima.)
Gas
The weekly gas consumption in 1000s of cubic feet.

SOURCE:

A data set collected in the 1960s by Mr Derek Whiteside of the UK~Building Research Station. Reported by

Hand, D. J., Daly, F., McConway, K., Lunn, D. and Ostrowski, E. eds (1993) A Handbook of Small Data Sets. Chapman & Hall, p. 69.

EXAMPLES:

xyplot(Gas ~ Temp | Insul, whiteside, panel =
  function(x, y, ...) {
     panel.xyplot(x, y, ...)
     panel.lmline(x, y, ...)
  }, xlab = "Average external temperature (deg. C)",
  ylab = "Gas consumption  (1000 cubic feet)")
gasB <- lm(Gas ~ Temp, whiteside, subset=Insul=="Before")
gasA <- update(gasB, subset=Insul=="After")
summary(gasB)
summary(gasA)
gasBA <- lm(Gas ~ Insul/Temp - 1, whiteside)
summary(gasBA)
gasQ <- lm(Gas ~ Insul/(Temp + I(Temp^2)) - 1, whiteside)
summary(gasQ)$coef
gasPR <- lm(Gas ~ Insul + Temp, whiteside)
anova(gasPR, gasBA)
options(contrasts = c("contr.treatment", "contr.poly"))
gasBA1 <- lm(Gas ~ Insul*Temp, whiteside)
summary(gasBA1)$coef