\name{locationTest}


\alias{locationTest}


\title{Two Sample Location Tests}


\description{
    
    Tests if two series differ in their distributional
    location parameter.

}


\usage{
locationTest(x, y, method = c("t", "kw2"), 
    title = NULL, description = NULL) 
}


\arguments{
  
    \item{x, y}{
        numeric vectors of data values.
        }
    \item{method}{
        a character string naming which test should be applied.
        } 
    \item{title}{
        an optional title string, if not specified the inputs data 
        name is deparsed.
        }
    \item{description}{
        optional description string, or a vector of character strings.
        } 
       
}


\value{

    In contrast to R's output report from S3 objects of class \code{"htest"}
    a different output report is produced. The classical tests presented
    here return an S4 object of class \code{"fHTEST"}. The object contains
    the following slots:
    
    \item{@call}{
        the function call.  
        }
    \item{@data}{
        the data as specified by the input argument(s).
        }
    \item{@test}{
        a list whose elements contain the results from the statistical
        test. The information provided is similar to a list object of
        class \code{"htest"}.
        }
    \item{@title}{
        a character string with the name of the test. This can be 
        overwritten specifying a user defined input argument.
        }
    \item{@description}{
        a character string with an optional user defined description. 
        By default just the current date when the test was applied will
        be returned.
        }
    
    
    The slot \code{@test} returns an object of class \code{"list"} 
    containing (at least) the following elements:

    \item{statistic}{
        the value(s) of the test statistic.
        }
    \item{p.value}{
        the p-value(s) of the test.
        }
    \item{parameters}{
        a numeric value or vector of parameters.
        }
    \item{estimate}{
        a numeric value or vector of sample estimates.
        }
    \item{conf.int}{
        a numeric two row vector or matrix of 95% confidence levels.
        }
    \item{method}{
        a character string indicating what type of test was performed.
        }
    \item{data.name}{
        a character string giving the name(s) of the data.
        }
}


\details{
    
  
    The \code{method="t"} can be used to determine if the two sample 
    means are equal for unpaired data sets. Two variants are used,
    assuming equal or unequal variances. 
  
    The \code{method="kw2"} performs a Kruskal-Wallis rank sum 
    test of the null hypothesis that the central tendencies or medians of 
    two samples are the same. The alternative is that they differ. 
    Note, that it is not assumed that the two samples are drawn from the 
    same distribution. It is also worth to know that the test assumes 
    that the variables under consideration have underlying continuous 
    distributions.

}

\note{

    Some of the test implementations are selected from \R's \code{ctest} 
    package.  
       
}


\references{

Conover, W. J. (1971);
    \emph{Practical nonparametric statistics},
    New York: John Wiley & Sons.

Lehmann E.L. (1986); 
    \emph{Testing Statistical Hypotheses}, 
    John Wiley and Sons, New York.

}


\author{

    R-core team for hypothesis tests implemented from \R's 
    package \code{ctest}.
    
}


\examples{
## rnorm - 
   # Generate Series:
   x = rnorm(50)
   y = rnorm(50)
  
## locationTest -
   locationTest(x, y, "t")
   locationTest(x, y, "kw2")

}


\keyword{htest}

