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From |
"Mike Kim" <kalisperos@gmail.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: Creating interaction and square variables |

Date |
Thu, 30 Aug 2012 19:49:08 -0500 |

Thanks, Dimitriy. I changed the code like the following and it works. I am still curious because the first "if" works well. I am using Stata 12. forv i=1/22 { forv j=1/22 { gen f`i'f`j'=firm`i'*firm`j' if `i'<=`j' } } forv i=1/22 { forv j=1/22 { if `i' >`j' { drop f`i'f`j' } } } Mike. -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Dimitriy V. Masterov Sent: Thursday, August 30, 2012 7:31 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: Creating interaction and square variables Mike, You are not understanding how if works. Take a look at this: http://www.stata.com/help.cgi?ifcmd Depending on which version of Stata you have, you also might want to look into factor variable notation to do this for you on the fly. DVM On Thu, Aug 30, 2012 at 3:39 PM, Mike Kim <kalisperos@gmail.com> wrote: > Hi all, > > I would like to create interaction and square variables. Let say, I > have three variables x1, x2, x3. > > I used to the following code to create interactions and square of x1, > x2, x3. > > forv i=1/3 { > forv j=1/3 { > gen x`i'x`j'=x`i'*x`j' // if `i'<=`j' : This still creates variables > with missing values. > } > } > > Since x1*x2 = x2*x1, for example, I tried to drop those same variables > using the following code, but got error message: "invalid syntax, r(198)". > > forv i=1/3 { > forv j=1/3 { > drop x`i'x`j' if `i'<`j' > } > } > > Can you please let me know what is wrong in the code? Thank you for > your help in advance. > > Mike. > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Creating interaction and square variables***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: Creating interaction and square variables***From:*"Mike Kim" <kalisperos@gmail.com>

**Re: st: Creating interaction and square variables***From:*"Dimitriy V. Masterov" <dvmaster@gmail.com>

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