predict-methods {bbmle} R Documentation

## Predicted values from an mle2 fit

### Description

Given an mle2 fit and an optional list of new data, return predictions (more generally, summary statistics of the predicted distribution)

### Usage

    ## S4 method for signature 'mle2'
predict(object, newdata=NULL,
location="mean", newparams=NULL, ...)
## S4 method for signature 'mle2'
simulate(object, nsim,
seed, newdata=NULL, newparams=NULL, ...)
## S4 method for signature 'mle2'
residuals(object,type=c("pearson","response"),
location="mean",...)


### Arguments

 object an mle2 object newdata optional list of new data newparams optional vector of new parameters location name of the summary statistic to return nsim number of simulations seed random number seed type residuals type ... additional arguments (for generic compatibility)

### Methods

x = "mle2"

an mle2 fit

### Note

For some models (e.g. constant models), predict may return a single value rather than a vector of the appropriate length.

### Examples

set.seed(1002)
lymax <- c(0,2)
lhalf <- 0
x <- runif(200)
g <- factor(rep(c("a","b"),each=100))
y <- rnbinom(200,mu=exp(lymax[g])/(1+x/exp(lhalf)),size=2)
dat <- data.frame(y,g,x)

fit3 <- mle2(y~dnbinom(mu=exp(lymax)/(1+x/exp(lhalf)),size=exp(logk)),
parameters=list(lymax~g),
start=list(lymax=0,lhalf=0,logk=0),
data=dat)

plot(y~x,col=g)
## true curves
curve(exp(0)/(1+x/exp(0)),add=TRUE)
curve(exp(2)/(1+x/exp(0)),col=2,add=TRUE)
## model predictions
xvec = seq(0,1,length=100)
lines(xvec,predict(fit3,newdata=list(g=factor(rep("a",100),levels=c("a","b")),
x = xvec)),col=1,lty=2)
lines(xvec,predict(fit3,newdata=list(g=factor(rep("b",100),levels=c("a","b")),
x = xvec)),col=2,lty=2)

## comparing automatic and manual predictions
p1 = predict(fit3)
p2A =
with(as.list(coef(fit3)),exp(lymax.(Intercept))/(1+x[1:100]/exp(lhalf)))
p2B =
with(as.list(coef(fit3)),exp(lymax.(Intercept)+lymax.gb)/(1+x[101:200]/exp(lhalf)))
all(p1==c(p2A,p2B))
##
simulate(fit3)


[Package bbmle version 1.0.25 Index]