# gam.exact: A method for gam producing asymptotically exact standard... In gam: Generalized Additive Models

 gam.exact R Documentation

## A method for gam producing asymptotically exact standard errors for linear estimates

### Description

This function is a "wrapper" for a Gam object, and produces exact standard errors for each linear term in the gam call (except for the intercept).

### Usage

``````gam.exact(Gam.obj)
``````

### Arguments

 `Gam.obj` a Gam object

### Details

Only standard errors for the linear terms are produced. There is a print method for the Gamex class.

### Value

A list (of class Gamex) containing a table of coefficients and a variance covariance matrix for the linear terms in the formula of the gam call.

### Author(s)

Aidan McDermott, Department of Biostatistics, Johns Hopkins University. Modified by Trevor Hastie for R

### References

Issues in Semiparametric Regression: A Case Study of Time Series Models in Air Pollution and Mortality, Dominici F., McDermott A., Hastie T.J., JASA, December 2004, 99(468), 938-948. See https://hastie.su.domains/Papers/dominiciR2.pdf

### Examples

``````
set.seed(31)
n     <- 200
x     <- rnorm(n)
y     <- rnorm(n)
a     <- rep(1:10,length=n)
b     <- rnorm(n)
z     <- 1.4 + 2.1*a + 1.2*b + 0.2*sin(x/(3*max(x))) + 0.3*cos(y/(5*max(y))) + 0.5 * rnorm(n)
dat   <- data.frame(x,y,a,b,z,testit=b*2)
### Model 1: Basic
Gam.o <- gam(z ~ a + b + s(x,3) + s(y,5), data=dat)
coefficients(summary.glm(Gam.o))
gam.exact(Gam.o)
### Model 2: Poisson
Gam.o <- gam(round(abs(z)) ~ a + b + s(x,3) + s(y,5), data=dat,family=poisson)
coefficients(summary.glm(Gam.o))
gam.exact(Gam.o)

``````

gam documentation built on March 31, 2023, 9:10 p.m.