FlexParamCurve (version 1.3)

posneg_data: Simulated growth of black-browed albatrosses

Description

The posneg_data data frame has 1300 rows and 3 columns of records of the simulated masses for black-browed albatross chicks between 0 and 166 days of age.

Usage

data(posneg_data)

source

Huin, N. & Prince, P.A. (2000) Chick growth in albatrosses: curve fitting with a twist. Journal of Avian Biology, 31, 418-425.

Details

No published parameter estimates with associated variability are available for positive-negative growth curves. These data were simulated using an 8-parameter positive-negative Richards curve (SSposnegRichards (model 1)), using parameters drawn from normal distributions with the following means (standard deviations): Asym=4300 (180) K=0.06 (0.01) Infl=23 (0.4) M=0.1 (0.05) RAsym=1433.3 (540) #1/3 of Asym, more variable Rk=0.108 (0.03) #1.8 times faster recession, more variable Ri=Infl+87.259 (1.7) # more variable but linked to Infl RM=M (0.15) #more variable These values were chosen through comparison of growth curves with Huin and Prince (2000) Fig 2 and variability observed between individual chicks of little penguins in a 10 year dataset (Chiaradia and Nisbet unpublished data). Each simulated individual had 13 measurements stratified through the development period, with 1-13 day random differences in timing of each measurement. This data object has methods for nlme grouped-data classes.

Examples

require(stats); require(graphics)
data(posneg_data)
modpar(posneg_data$age, posneg_data$mass) #create pnmodelparams for fixed parameters
plot(mass ~ age, data = posneg_data, subset = id == "1",
     xlab = "Chick age (day)", las = 1,
     ylab = "Chick mass (g)",
     main = "posneg_data data and fitted curve (Chick #1 only)")
fm1 <- nls(mass ~ SSposnegRichards(age,Asym=Asym,K=K,Infl=Infl, RAsym=RAsym,
           Rk=Rk,Ri=Ri,modno=22),
           data = posneg_data, subset = id == "1")
age <- seq(0, 166, length.out = 101)
lines(age, predict(fm1, list(age = age)))