DescTools (version 0.99.14)

SignTest: Sign Test

Description

Performs one- and two-sample sign tests on vectors of data.

Usage

SignTest(x, ...)

## S3 method for class 'default':
SignTest(x, y = NULL, alternative = c("two.sided", "less", "greater"), 
         mu = 0, conf.level = 0.95, ...)

## S3 method for class 'formula':
SignTest(formula, data, subset, na.action, \dots)

Arguments

x
numeric vector of data values. Non-finite (e.g. infinite or missing) values will be omitted.
y
an optional numeric vector of data values: as with x non-finite values will be omitted.
mu
a number specifying an optional parameter used to form the null hypothesis. See Details.
alternative
is a character string, one of "greater", "less", or "two.sided", or the initial letter of each, indicating the specification of the alternative hypothesis. For one-sample tests, alternative refe
conf.level
confidence level for the returned confidence interval, restricted to lie between zero and one.
formula
a formula of the form lhs ~ rhs where lhs gives the data values and rhs the corresponding groups.
data
an optional matrix or data frame (or similar: see model.frame) containing the variables in the formula formula. By default the variables are taken from environment(formula)
subset
an optional vector specifying a subset of observations to be used.
na.action
a function which indicates what should happen when the data contain NAs. Defaults to getOption("na.action").
...
further arguments to be passed to or from methods.

Value

  • A list of class htest, containing the following components:
  • statisticthe S-statistic (the number of positive differences between the data and the hypothesized median), with names attribute S.
  • parameterthe total number of valid differences.
  • p.valuethe p-value for the test.
  • null.valueis the value of the median specified by the null hypothesis. This equals the input argument mu.
  • alternativea character string describing the alternative hypothesis.
  • methodthe type of test applied.
  • data.namea character string giving the names of the data.
  • conf.inta confidence interval for the median.
  • estimatethe sample median.

Details

The formula interface is only applicable for the 2-sample test. SignTest computes a Dependent-samples Sign-Test if both x and y are provided. If only x is provided, the One-sample Sign-Test will be computed. For the one-sample sign-test, the null hypothesis is that the median of the population from which x is drawn is mu. For the two-sample dependent case, the null hypothesis is that the median for the differences of the populations from which x and y are drawn is mu. The alternative hypothesis indicates the direction of divergence of the population median for x from mu (i.e., "greater", "less", "two.sided".) The confidence levels are exact.

References

Gibbons, J.D. and Chakraborti, S. (1992): Nonparametric Statistical Inference. Marcel Dekker Inc., New York. Kitchens, L. J. (2003): Basic Statistics and Data Analysis. Duxbury. Conover, W. J. (1980): Practical Nonparametric Statistics, 2nd ed. Wiley, New York.

See Also

t.test, wilcox.test, ZTest, binom.test, SIGN.test in the package BSDA (reporting approximative confidence intervals).

Examples

Run this code
x <- c(1.83,  0.50,  1.62,  2.48, 1.68, 1.88, 1.55, 3.06, 1.30)
y <- c(0.878, 0.647, 0.598, 2.05, 1.06, 1.29, 1.06, 3.14, 1.29)

SignTest(x, y)
wilcox.test(x, y, paired = TRUE)


d.light <- data.frame( 
  black = c(25.85,28.84,32.05,25.74,20.89,41.05,25.01,24.96,27.47),
  white <- c(18.23,20.84,22.96,19.68,19.5,24.98,16.61,16.07,24.59),
  d <- c(7.62,8,9.09,6.06,1.39,16.07,8.4,8.89,2.88)
)

d <- d.light$d

SignTest(x=d, mu = 4)
wilcox.test(x=d, mu = 4, conf.int = TRUE)

SignTest(x=d, mu = 4, alternative="less")
wilcox.test(x=d, mu = 4, conf.int = TRUE, alternative="less")

SignTest(x=d, mu = 4, alternative="greater")
wilcox.test(x=d, mu = 4, conf.int = TRUE, alternative="greater")

# test die interfaces
x <- runif(10)
y <- runif(10)
g <- rep(1:2, each=10) 
xx <- c(x, y)

SignTest(x ~ group, data=data.frame(x=xx, group=g ))
SignTest(xx ~ g)
SignTest(x, y)

SignTest(x - y)

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