The data set used in this package are collected by Dr Peggy Braun (University of Leipzig) and passed on to use by professor Jane Sutherland of London Metropolitan University.
It consists of experimental enzymology results from a research project which attempted to develop a generic food spoilage model.
The data set contains a column called NAMES, which shows the experiment name,
three columns with values of the environmental conditions: temperature (Tem),
pH and water activity (aw), and the rest of the columns
contains the activity of the cocktails, observed at certain days.
The researchers recorded the activity of proteases and lipases in each cocktail and were interested in predicting the time when the activity started given the environmental conditions. The activity is a positive integer and enzymes are considered inactive when activity=0.
data(lip)A data frame with 120 observations on the following 14 variables.
namea factor with levels the different experiment
Tema numeric vector showing the temperature
pHa numeric vector PH
awa numeric vector water activity
X0.da numeric vector if enzyme reacted at day 0
X1.da numeric vector if enzyme reacted at day 1
X2.da numeric vector if enzyme reacted at day 2
X4.da numeric vector if enzyme reacted at days 3 or 4
X11.da numeric vector if enzyme reacted at days 5 to 11
X18d.a numeric vector if enzyme reacted at days 12 to q18
X25.da numeric vector if enzyme reacted at days 19 to 25
X32.da numeric vector if enzyme reacted at days 26 to 32
X39.da numeric vector if enzyme reacted at days 33 to 39
ya matrix with 3 columns: this is a Surv()
object indicating the start the finish and censored indicator as defined in
function Surv() of survival.