basicTrendline (version 2.0.3)

SSpower3P: Self-Starting Nls 'power3P' Regression Model

Description

This selfStart model evaluates the power regression function (formula as: y=a*x^b+c). It has an initial attribute that will evaluate initial estimates of the parameters a, b, and c for a given set of data.

Usage

SSpower3P(predictor, a, b, c)

Arguments

predictor

a numeric vector of values at which to evaluate the model.

a, b, c

Three numeric parameters responsing to the exp3P model.

See Also

trendline, SSexp3P, SSpower3P, nls, selfStart

Examples

# NOT RUN {
library(basicTrendline)
x<-1:5
y<-c(2,4,8,20,25)
xy<-data.frame(x,y)
getInitial(y ~ SSpower3P(x,a,b,c), data = xy)
## Initial values are in fact the converged values

fitpower3P <- nls(y~SSpower3P(x,a,b,c), data=xy)
summary(fitpower3P)

# }