No
| Crude oil sample identification label. (factor) |
SG
| Specific gravity, degrees API. (Constant within sample.) |
VP
| Vapour pressure in psi. (Constant within sample.) |
V10
| Volatility of crude; ASTM 10% point. (Constant within sample.) |
EP
| Desired volatility of gasoline. (The end point. Varies within sample.) |
Y
| Yield as a percentage of crude. |
These data were originally used by Prater (1956) to build an estimation equation for the yield of the refining process of crude oil to gasoline.
This dataset is also given in D. J. Hand, F. Daly, K. McConway, D. Lunn, and E. Ostrowski E. (eds) (1993) A Handbook of Small Data Sets. Chapman & Hall.
library(lme) data(petrol) Petrol <- petrol Petrol[, 2:5] <- scale(as.matrix(Petrol[, 2:5]), scale = F) pet3.lme <- lme(Y ~ SG + VP + V10 + EP, random = ~ 1 | No, data = Petrol, REML=T) pet3.lme <- update(pet3.lme, REML=F) pet4.lme <- update(pet3.lme, fixed = Y ~ V10 + EP) anova(pet4.lme, pet3.lme)