Pixel dataset

X-ray pixel intensities over time

The Pixel data frame has 102 rows and 4 columns of data on the pixel intensities of CT scans of dogs over time

Format

This data frame contains the following columns:

• Dog: a factor with levels 1 to 10 designating the dog on which the scan was made
• Side: a factor with levels L and R designating the side of the dog being scanned
• day: a numeric vector giving the day post injection of the contrast on which the scan was made
• pixel: a numeric vector of pixel intensities

Source

Pinheiro, J. C. and Bates, D. M. (2000) Mixed-effects Models in S and S-PLUS, Springer.

Examples

fm1 <- lme(pixel ~ day + I(day^2), data = Pixel,
           random = list(Dog = ~ day, Side = ~ 1))
summary(fm1)
VarCorr(fm1)