statistic-methods {coin} R Documentation

## Extraction of the Test Statistic and the Linear Statistic

### Description

Methods for extraction of the test statistic and the linear statistic.

### Usage

```## S4 method for signature 'IndependenceLinearStatistic'
statistic(object, type = c("test", "linear", "centered", "standardized"),
partial = FALSE, ...)
## S4 method for signature 'IndependenceTestStatistic'
statistic(object, type = c("test", "linear", "centered", "standardized"),
partial = FALSE, ...)
## S4 method for signature 'IndependenceTest'
statistic(object, type = c("test", "linear", "centered", "standardized"),
partial = FALSE, ...)
```

### Arguments

 `object` an object from which the test statistic or the linear statistic can be extracted. `type` a character string indicating the type of statistic: either `"test"` (default) for the test statistic, `"linear"` for the unstandardized linear statistic, `"centered"` for the centered linear statistic or `"standardized"` for the standardized linear statistic. `partial` a logical indicating that the partial linear statistic for each block should be extracted. Defaults to `FALSE`. `...` further arguments (currently ignored).

### Details

The method `statistic` extracts the univariate test statistic or the, possibly multivariate, linear statistic in its unstandardized, centered or standardized form.

The test statistic (`type = "test"`) is returned by default. The unstandardized, centered or standardized linear statistic is obtained by setting `type` to `"linear"`, `"centered"` or `"standardized"`, respectively. For tests of conditional independence within blocks, the partial linear statistic for each block is obtained by setting `partial = TRUE`.

### Value

The test statistic or the unstandardized, centered or standardized linear statistic extracted from `object`. A numeric vector, matrix or array.

### Examples

```## Example data
dta <- data.frame(
y = gl(4, 5),
x = gl(5, 4)
)

## Asymptotic Cochran-Mantel-Haenszel Test
ct <- cmh_test(y ~ x, data = dta)

## Test statistic
statistic(ct)

## The unstandardized linear statistic...
statistic(ct, type = "linear")

## ...is identical to the contingency table
xtabs(~ x + y, data = dta)

## The centered linear statistic...
statistic(ct, type = "centered")

## ...is identical to
statistic(ct, type = "linear") - expectation(ct)

## The standardized linear statistic, illustrating departures from the null
## hypothesis of independence...
statistic(ct, type = "standardized")

## ...is identical to
(statistic(ct, type = "linear") - expectation(ct)) / sqrt(variance(ct))
```

[Package coin version 1.4-1 Index]