{smcl}
{* version 1.0.4 11jun2011}
{cmd:help joinvars}
{hline}

{title:Title}

{p 5}
{cmd:joinvars} {hline 2} Join values of variables

{title:Syntax}

{p 8}
{cmd:joinvars} {newvar} [=] {varlist} {ifin} 
[{cmd:,} {opt update} {opt miss:ok} {opt double}]

{p 8}
{helpb by} is allowed


{title:Description}

{pstd}
{cmd:joinvars} creates variable {it:newvar} containing joined values 
of {it:varlist}. Starting with a copy of the first variable in 
{it:varlist}, missing values in {it:newvar} are replaced with values 
of the next variable(s) in {it:varlist}.

{title:Options}

{dlgtab:Options}

{phang}
{opt upd:ate} replaces non-missing values in {it:newvar} with values 
of variables in {it:varlist}. Default is to replace missing values only.

{phang}
{opt miss:ok} replaces non-missing values in {it:newvar} with missing 
values of variables in {it:varlist}. Only affects {opt update}.

{phang}
{opt double} create {it:newvar} with storage {help data_types:type} 
double. May only be specified if variables in {it:varlist} are numeric.


{title:Example}

{pstd}
Firstly, I separate wages by race in the NLSW 1988 dataset using 
{help separate}.

	. sysuse nlsw88 ,clear
	(NLSW, 1988 extract)

	. separate wage ,by(race)

	[output omitted]

{pstd}
Now suppose the original variable {it:wage} is missing in this dataset. 
It can be created using {cmd: joinvars}.

	. drop wage

	. list race wage* in 516/520

	     +----------------------------------------+
	     |  race      wage1      wage2      wage3 |
	     |----------------------------------------|
	516. | white   4.428341          .          . |
	517. | white   15.09662          .          . |
	518. | black          .   6.843801          . |
	519. | other          .          .   6.513685 |
	520. | white   5.072463          .          . |
	     +----------------------------------------+

	{cmd:. joinvars wage = wage1 wage2 wage3}

	. list race wage1 wage2 wage3 wage in 516/520

	     +---------------------------------------------------+
	     |  race      wage1      wage2      wage3       wage |
	     |---------------------------------------------------|
	516. | white   4.428341          .          .   4.428341 |
	517. | white   15.09662          .          .   15.09662 |
	518. | black          .   6.843801          .   6.843801 |
	519. | other          .          .   6.513685   6.513685 |
	520. | white   5.072463          .          .   5.072463 |
	     +---------------------------------------------------+

	{cmd:. joinvars nonsense = wage1 wage2 wage3 ,update missok}

	. list race wage1 wage2 wage3 nonsense in 516/520

	     +---------------------------------------------------+
	     |  race      wage1      wage2      wage3   nonsense |
	     |---------------------------------------------------|
	516. | white   4.428341          .          .          . |
	517. | white   15.09662          .          .          . |
	518. | black          .   6.843801          .          . |
	519. | other          .          .   6.513685   6.513685 |
	520. | white   5.072463          .          .          . |
	     +---------------------------------------------------+

 
{title:Author}

{pstd}Daniel Klein, University of Bamberg, klein.daniel.81@gmail.com

{title:Also see}

{psee}
Online: {help separate}, {help egen}, {help reshape}
{p_end}
