{smcl}
{* 6December2012}{...}
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help for {hi:clv}{right:Jean-Benoit Hardouin}
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{title:Clustering of variables around latent components }

{p 8 14 2}{cmd:clv} [{it:varlist}] [{cmd:if} {it:exp}] [{cmd:in} {it:range}] [{cmd:weight}]
[{cmd:,} {cmdab:nostand:ardized} {cmdab:bar} {cmdab:cons:olidation}({it:#})
{cmdab:noden:dro} {cmdab:saved:endro}({it:filename}[,replace]) {cmdab:cut:number}({it:#}) {cmdab:show:count} {cmdab:texts:ize}({it:string})
{cmdab:deltaT} {cmdab:hor:izontal} {cmdab:abb:rev}({it:#}) {cmdab:tit:le}({it:string})
{cmdab:cap:tion}({it:string}) {cmdab:ker:nel}({it:numlist})
{cmdab:meth:od}({it:keyword}) {cmdab:nobip:lot} {cmdab:add:var} {cmd:genlv}(string) {cmdab:rep:lace} {cmd:std} {cmd:dim}({it:string})]

{title:Description}

{p 4 8 2}{cmd:clv} clusters variables around latent components. The variables are clustered stepwise by
seeking to minimize at each step the decrease of the T criterion, computed as the sum of the
first eigenvalues of the matrices of data of all the clusters. A hierarchical cluster analysis
based on this criterion is performed. A consolidation procedure can be run subsequently which
allows each variable to be assigned to the latent component it is the most correlated with.

{title:Options}

{p 4 8 2}{cmd:nostandardized} uses centered variables instead of standardized variables.

{p 4 8 2}{cmd:bar} displays a chart of the decrease in the T criterion at each step.

{p 4 8 2}{cmd:consolidation} performs a consolidation procedure with the obtained partition into the specified number of clusters (by default, no consolidation procedure is performed).

{p 4 8 2}{cmd:nodendro} suppresses the display of the dendogram.

{p 4 8 2}{cmd:savedendro} saves the dendrogram in the file defined by this option. If this file already exists, it is possible to replace it with the {cmd:replace} option.

{p 4 8 2}{cmd:cutnumber} defines the number of clusters presented in the dendrogram (40 by default).

{p 4 8 2}{cmd:showcount} displays the number of variables in each cluster (usefull with the {cmd:cutnumber} option).

{p 4 8 2}{cmd:textsize} defines the size of the labels of the variables on the dendrogram (see {help textsizestyle}).

{p 4 8 2}{cmd:deltaT} uses the variation of the T criterion as height variable for the dendrogram.

{p 4 8 2}{cmd:horizontal} displays an horizontal (instead vertical) dendrogram.

{p 4 8 2}{cmd:abbrev} defines the length of the variables labels on the dendrogram (15 characters by default).

{p 4 8 2}{cmd:title} defines the title of the dendrogram.

{p 4 8 2}{cmd:caption} defines the caption of the axis of the dendrogram which indicates the names of the variables.

{p 4 8 2}{cmd:kernel} defines one or several kernels of variables (variables which are clustered together in an initial step). The first number indicates that the first variables are clustered together, the second number indicates that the
following variables are clustered together...

{p 4 8 2}{cmd:method} indicates the method to cluster the variables among {it:classical}
(by default) for the method described by Vigneau and Qannari, {it:polychoric} for a use of
the matrix of polychoric coefficients of correlation (instead of Pearson coefficients of
correlation), {it:v2} for a modified algorithm wich search to minimize the maximum
second eigenvalue among the clusters of 2 variables and more, {it:polychoricv2} which
correspond to the {it:v2} option with the matrix of polychoric coefficients of correlation,
and {it:centroid} which is defined by Vigneau and Qannari as an adaptation of CLV when
the sign of the correlation coefficients between the variables is important.

{p 4 8 2}{cmd:nobiplot} avoids to display a biplot of the latent variables with the {cmd:consolidation} option.

{p 4 8 2}{cmd:genlv} saves the latent variables in new variables with the string as prefix (followed by a number). This option must be used in conjonction with the {cmd:consolidation} option.

{p 4 8 2}{cmd:replace} allows replacing the variables creates with the {cmd:genlv} option if they already exist.

{p 4 8 2}{cmd:std} allows standardizing the latent variables for the graphical representation on the biplot.

{p 4 8 2}{cmd:dim}({it:string}) allows choosing the axes represented on the biplot.

{p 4 8 2} If no {it:varlist} is indicated, the procedure uses the varlist from the last {cmd:clv} procedure, but does not perform the hierarchical cluster analysis.

{title:Notes}

{p 4 8 2} The classifications around latent variables (CLV) is defined by its authors (Vigneau and Qannari, 2003) only for continuous variables. Results with binary or ordinal variables must be interpreted with precautions.

{p 4 8 2} Only {cmd:fweights} are allowed. The biplots are disabled if weights are used.

{p 4 8 2} In this procedure, all the individuals with at least one missing value are omitted.

{p 4 8 2} With the {it:polychoric} and {it:polychoricv2} methods, the {cmd:nostandardized} option is disabled.

{p 4 8 2} This module uses the following modules downloadable on SSC: {stata ssc describe polychoric}, {stata ssc describe biplotvlab} and {stata ssc describe genscore}

{title:Example}

	{p 4 8 2}{cmd:. clv var1-var15} /*performs the HCA procedure*/

	{p 4 8 2}{cmd:. clv var1-var15, cons(6) bar nodendro meth(centroid)} /* performs the HCA procedure based on the centroid method followed by a consolidation procedure with 6 clusters*/

	{p 4 8 2}{cmd:. clv, cons(3)  addvar} /*performs only the consolidation procedure with 3 clusters, based on the preceeding HCA procedure*/

{title:Aknowledgements}

{p 4 8 2} The author thanks Ronan Conroy for all the propositions of improvements.

{title:Reference}

{p 4 8 2} Vigneau E. and Qannari E. M. Clustering of variables around latent components. Communications in Statistics - Simulation and Computation. 32(4): 1131-1150, 2003.

{title:Author}

{p 4 8 2}Jean-Benoit Hardouin, PhD, assistant professor{p_end}
{p 4 8 2}EA 4275 SPHERE "Team of Biostatistics, Clinical Research and Subjective Measures in Health Sciences"{p_end}
{p 4 8 2}University of Nantes - Faculty of Pharmaceutical Sciences{p_end}
{p 4 8 2}1, rue Gaston Veil - BP 53508{p_end}
{p 4 8 2}44035 Nantes Cedex 1 - FRANCE{p_end}
{p 4 8 2}Email:
{browse "mailto:jean-benoit.hardouin@univ-nantes.fr":jean-benoit.hardouin@univ-nantes.fr}{p_end}
{p 4 8 2}Website {browse "http://www.anaqol.org":AnaQol}