| Line 36... |
Line 36... |
| 36 |
two variances as being equal. If \code{TRUE} then the pooled
|
36 |
two variances as being equal. If \code{TRUE} then the pooled
|
| 37 |
variance is used to estimate the variance otherwise the Welch
|
37 |
variance is used to estimate the variance otherwise the Welch
|
| 38 |
(or Satterthwaite) approximation to the degrees of freedom is used.}
|
38 |
(or Satterthwaite) approximation to the degrees of freedom is used.}
|
| 39 |
\item{conf.level}{confidence level of the interval.}
|
39 |
\item{conf.level}{confidence level of the interval.}
|
| 40 |
\item{formula}{a formula of the form \code{lhs ~ rhs} where \code{lhs}
|
40 |
\item{formula}{a formula of the form \code{lhs ~ rhs} where \code{lhs}
|
| 41 |
is a numeric variable giving the data values and \code{rhs} a factor
|
41 |
is a numeric variable giving the data values and \code{rhs} either
|
| - |
|
42 |
\code{1} for a one-sample or paired test or a factor
|
| 42 |
with two levels giving the corresponding groups.}
|
43 |
with two levels giving the corresponding groups. If \code{lhs} is of
|
| - |
|
44 |
class \code{"Pair"} and \code{rhs} is \code{1}, a paired test is done}
|
| 43 |
\item{data}{an optional matrix or data frame (or similar: see
|
45 |
\item{data}{an optional matrix or data frame (or similar: see
|
| 44 |
\code{\link{model.frame}}) containing the variables in the
|
46 |
\code{\link{model.frame}}) containing the variables in the
|
| 45 |
formula \code{formula}. By default the variables are taken from
|
47 |
formula \code{formula}. By default the variables are taken from
|
| 46 |
\code{environment(formula)}.}
|
48 |
\code{environment(formula)}.}
|
| 47 |
\item{subset}{an optional vector specifying a subset of observations
|
49 |
\item{subset}{an optional vector specifying a subset of observations
|
| Line 99... |
Line 101... |
| 99 |
|
101 |
|
| 100 |
## Classical example: Student's sleep data
|
102 |
## Classical example: Student's sleep data
|
| 101 |
plot(extra ~ group, data = sleep)
|
103 |
plot(extra ~ group, data = sleep)
|
| 102 |
## Traditional interface
|
104 |
## Traditional interface
|
| 103 |
with(sleep, t.test(extra[group == 1], extra[group == 2]))
|
105 |
with(sleep, t.test(extra[group == 1], extra[group == 2]))
|
| - |
|
106 |
|
| 104 |
## Formula interface
|
107 |
## Formula interface
|
| 105 |
t.test(extra ~ group, data = sleep)
|
108 |
t.test(extra ~ group, data = sleep)
|
| - |
|
109 |
|
| - |
|
110 |
## Formula interface to one-sample test
|
| - |
|
111 |
t.test(extra ~ 1, data = sleep)
|
| - |
|
112 |
|
| - |
|
113 |
## Formula interface to paired test
|
| - |
|
114 |
## The sleep data are actually paired, so could have been in wide format:
|
| - |
|
115 |
sleep2 <- reshape(sleep, direction = "wide",
|
| - |
|
116 |
idvar = "ID", timevar = "group")
|
| - |
|
117 |
t.test(Pair(extra.1, extra.2) ~ 1, data = sleep2)
|
| 106 |
}
|
118 |
}
|
| 107 |
\keyword{htest}
|
119 |
\keyword{htest}
|
The R Project SVN
R