a numeric vector.
NAs
and
Infs are allowed but will be removed.
If
groups.p is
FALSE,
x is the first sample.
If
groups.p is
TRUE,
x is the response variable of two samples
and
y is the grouping indicator.
y
a numeric vector.
NAs
and
Infs are allowed but will be removed.
If
t.paired="Paired t",
then
x and
y must have the same
length, and observation pairs
x[i],
y[i] with at least
one
NA or
Inf will be removed.
If
groups.p is
FALSE,
y is the second sample.
If groups.p is
TRUE,
y is the grouping indicator with the first observation
indicating the first sample.
Only two groups are allowed.
OPTIONAL ARGUMENTS:
data
a data frame in which to interpret the variables named in the
x and
y.
If this is missing, then
x and
y must be two vectors.
groups.p
if
TRUE,
x is the response variable of two samples
and
y is the grouping indicator.
If
FALSE,
x is the first sample and
y is the second sample.
mu
a single number representing the value of the mean or
difference in means specified by the null hypothesis.
alternative
a character string, one of
"greater",
"less"
or
"two.sided", or just the initial letter of each, indicating
the specification of the alternative hypothesis.
For the paired t-tests,
alternative refers to
the true mean of the parent population in relation to the
hypothesized value
mu.
For the standard and Welch modified two-sample t-tests,
alternative refers to the difference
between the true population mean for
x
and that for
y, in relation to
mu.
t.paired
if
"Paired t",
x and
y are considered as paired vectors.
var.equal
if
TRUE, the variances of the parent
populations of
x and
y are assumed equal.
This should be supplied only for the two-sample
(i.e., unpaired) tests.
conf.level
confidence level for the returned confidence interval,
restricted to lie between zero and one.
print.object.p
if
TRUE, the result of the test is printed.
VALUE:
a list of class
"htest".
See the help file for
t.test for details.