| epi.eff {Epi} | R Documentation |
The function calculates the effects of an exposure on a response, possibly stratified by a stratifying variable, and/or controlled for one or more confounding variables.
epi.eff(response, type = "metric", exposure, strata = NULL, control = NULL, fup = NULL, data = NULL)
response |
The response variable - must be numeric |
type |
The type of responsetype - must be one of "metric",
"binary", "failure", or "count" |
exposure |
The exposure variable can be numeric or a factor |
strata |
The strata stratifying variable - must be a factor |
control |
The control variable(s) - must take the form
data.frame(variable names) |
fup |
The fup variable contains the follow-up time for a
failure response |
data |
data refers to the data frame used |
epi.eff(), without arguments, produces a list of arguments
comp1 |
Effects of exposure |
comp2 |
Tests of significance |
Michael Hills, mhills@blueyonder.co.uk
data(births)
attach(births)
hyp<-factor(hyp,labels=c("normal","hyper"))
sex<-factor(sex,labels=c("male","female"))
# bweight is the birth weight of the baby in gms, and is a metric response (the default)
# effect of hypertension on birth weight
epi.eff(bweight,exposure=hyp)
# effect of hypertension on birth weight stratified by sex
epi.eff(bweight,exposure=hyp,strata=sex)
# effect of hypertension on birth weight controlled for sex
epi.eff(bweight,exposure=hyp,control=data.frame(sex))
# effect of gestation time on birth weight
epi.eff(bweight,exposure=gestwks)
# effect of gestation time on birth weight stratified by sex
epi.eff(bweight,exposure=gestwks,strata=sex)
# effect of gestation time on birth weight controlled for sex
epi.eff(bweight,exposure=gestwks,control=data.frame(sex))
# lowbw is a binary response coded 1 for low birth weight and 0 otherwise
# effect of hypertension on low birth weight
epi.eff(lowbw,type="binary",exposure=hyp)
# effect of hypertension on low birth weight stratified by sex
epi.eff(lowbw,type="binary",exposure=hyp,strata=sex)
# effect of hypertension on low birth weight controlled for sex
epi.eff(lowbw,type="binary",exposure=hyp,control=data.frame(sex))
# effect of gestation time on low birth weight
epi.eff(lowbw,type="binary",exposure=gestwks)
# effect of gestation time on low birth weight stratified by sex
epi.eff(lowbw,type="binary",exposure=gestwks,strata=sex)
# effect of gestation time on low birth weight controlled for sex
epi.eff(lowbw,type="binary",exposure=gestwks,control=data.frame(sex))