{smcl}
{hline}
help for {cmd:checkvars} {right:Amadou B. DIALLO}
                         {right:Jean-Benoit HARDOUIN}
{hline}

{title:Allows checking whether a variable exists or not in a dataset.}


{p 4 8 2}{cmd:checkvars} {it:anything} [{cmd:,}
 {cmdab:t:olerance}({it:#}) {cmdab:ta:ble} {cmdab:nol:ist} {cmdab:nosu:m} 
 {cmdab:genm:iss}({it:newvarname})]

{title:Description}

{p 4 4 2}{cmd:checkvars} is a routine to check for existence of variables
within a (usually big) data set.

{p 4 4 2}{cmd:checkvars} searchs through the data whether each variable exists.
The variables are clustered between unavailable variables, available variables with 
a little amount of missing values and available variables with too many missing values.

{p 4 4 2}{cmd:isvar} must be installed ({stata ssc install isvar:ssc install isvar}).

{title:Options}

{p 4 4 2}{it:anything} is composed of variable names or lists of variables,

{p 4 4 2}{cmd:tolerance} is the tolerance level (in percentage) to consider a variable as available, with default 0,

{p 4 4 2}{cmd:nolist} avoids displaying availability status at the end of the process,

{p 4 4 2}{cmd:nosum} avoids displaying summary statistics of available variables,

{p 4 4 2}{cmd:table} displays the results in a table (instead as text),

{p 4 4 2}{cmd:genmiss} creates a new variable containing the number of missing values among the available variables.



{title:Saved results}

{p 4 4 2} {cmd:r(unavailable)} names of unavailable variables.{p_end}

{p 4 4 2} {cmd:r(available)}   names of available variables with a small amount of missing values.{p_end}

{p 4 4 2} {cmd:r(manymissings)} names of variables but with too missings.{p_end}

{title:Examples}

{p 4 4 2}{cmd:. use mydata, clear  }{p_end}

{p 4 4 2}{cmd:. checkvars x y z ,genmiss(countmiss) }{p_end}

{p 4 4 2}{cmd:. su `r(available)' }{p_end}

{p 4 4 2}{cmd:. tab countmiss }{p_end}

{p 4 4 2}{cmd:. u bigdataset in 1/100, clear // Big data set}{p_end}

{p 4 4 2}{cmd:. checkvars v1 v2 v3 xx yy , nosum tol(5) tab}{p_end}

{p 4 4 2}{cmd:. use `r(available)' using bigdataset, clear }{p_end}

{title:Remarks}

{p 4 4 2}{cmd:checkvars} and its primary versions ({cmd:checkfor} and {cmd:checkfor2}) have been primarily written for comparable surveys such as the Demography and 
Health Surveys (DHS) or the Multiple Indicator Cluster Surveys (MICS). But this could easily applied 
to any other survey.

{title:Authors}

{p 4 4 2}Amadou Bassirou DIALLO.
Poverty and Health Specialist. AFTPM, The World Bank.{p_end}
{p 4 4 2}Email: {browse "mailto:adiallo5@worldbank.org":adiallo5@worldbank.org}

{p 4 4 2}Jean-Benoit HARDOUIN.
Regional Health Observatory of Orléans, France.{p_end}
{p 4 4 2}Email: {browse "mailto:jean-benoit.hardouin@orscentre.org":jean-benoit.hardouin@orscentre.org}
 
{title:Aknowledgements}

{p 4 4 2}We would like to thank Christophe Rockmore and also Nick Cox 
and Kit Baum for their comments.

{title:Also see}

{p 4 13 2}Online:   help for {help checkfor}, {help checkfor2}, {help isvar}, {help nmissing}, {help npresent}, {help missing} and {help dropmiss} if installed.{p_end}