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From |
"Michael N. Mitchell" <Michael.Norman.Mitchell@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: is something wrong with fvvarlist "i(3 4).role"? |

Date |
Mon, 12 Jul 2010 18:56:12 -0700 |

Dear Lazlo

regress mpg i.rep78

. summ ibn.rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 1 | 69 .0289855 .1689948 0 1 2 | 69 .115942 .3225009 0 1 3 | 69 .4347826 .4993602 0 1 4 | 69 .2608696 .4423259 0 1 5 | 69 .1594203 .3687494 0 1

. fvset base none rep78 . summ i(1 2).rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 1 | 69 .0289855 .1689948 0 1 2 | 69 .115942 .3225009 0 1

Best regards, Michael N. Mitchell Data Management Using Stata - http://www.stata.com/bookstore/dmus.html A Visual Guide to Stata Graphics - http://www.stata.com/bookstore/vgsg.html Stata tidbit of the week - http://www.MichaelNormanMitchell.com On 2010-07-12 5.56 PM, László Sándor wrote:

Thank you, Michael! I acknowledge this behavior, but I find it strange (= not very intuitive for most uses of this) and also somewhat contrary to the manual's explanation (below). So I need to add another arbitrary level just to be able to introduce the level indicators I originally intended to? How clumsy... Thanks again, Laszlo Selecting levels You can select a range of levels -- a range of virtual variables -- by using the i(numlist). operator. Examples Description -------------------------------------------------------------------- i2.cat a single indicator for cat==2 2.cat same as i2.cat i(2 3 4).cat three indicators, cat==2, cat==3, and cat==4; same as i2.cat i3.cat i4.cat i(2/4).cat same as i(2 3 4).cat 2.cat#1.sex a single indicator that is 1 when cat==2 and sex==1, and is 0 otherwise i2.cat#i1.sex same as 2.cat#1.sex -------------------------------------------------------------------- On Tue, Jul 13, 2010 at 2:21 AM, Michael N. Mitchell <Michael.Norman.Mitchell@gmail.com> wrote:Greetings The trick is that the -i.- is creating a reference group, so in your example group 3 is the reference group. Here are some examples using the -auto- dataset. . sysuse auto (1978 Automobile Data) * group 1 is the reference, groups 2-5 are shown . summ i.rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 2 | 69 .115942 .3225009 0 1 3 | 69 .4347826 .4993602 0 1 4 | 69 .2608696 .4423259 0 1 5 | 69 .1594203 .3687494 0 1 * group 1 is the reference, groups 2-5 are shown . summ i(1/5).rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 2 | 69 .115942 .3225009 0 1 3 | 69 .4347826 .4993602 0 1 4 | 69 .2608696 .4423259 0 1 5 | 69 .1594203 .3687494 0 1 * group 1 is the reference, groups 2-4 are shown . summ i(1/4).rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 2 | 69 .115942 .3225009 0 1 3 | 69 .4347826 .4993602 0 1 4 | 69 .2608696 .4423259 0 1 * group 1 is the reference, groups 2-3 are shown . summ i(1/3).rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- rep78 | 2 | 69 .115942 .3225009 0 1 3 | 69 .4347826 .4993602 0 1 * group 1 is the reference, group 2 is shown . summ i(1/2).rep78 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- 2.rep78 | 69 .115942 .3225009 0 1 I hope that helps. Michael N. Mitchell Data Management Using Stata - http://www.stata.com/bookstore/dmus.html A Visual Guide to Stata Graphics - http://www.stata.com/bookstore/vgsg.html Stata tidbit of the week - http://www.MichaelNormanMitchell.com On 2010-07-12 4.21 PM, László Sándor wrote:Hi all, I think I have a straightforward question in the subject line. I use the up-to-date Stata on a mac. The factor variable handling does not work as promised in the manual (cf. -h fvvarlist-). See the most striking, simple example below. Or am I missing the obvious? Thank you, Laszlo . sum i(3 4).role Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- 4.role | 747 .2503347 .433496 0 1 . sum i(3/4).role Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- 4.role | 747 .2503347 .433496 0 1 * * 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/

* * 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/

**References**:**st: is something wrong with fvvarlist "i(3 4).role"?***From:*László Sándor <sandorl@gmail.com>

**Re: st: is something wrong with fvvarlist "i(3 4).role"?***From:*"Michael N. Mitchell" <Michael.Norman.Mitchell@gmail.com>

**Re: st: is something wrong with fvvarlist "i(3 4).role"?***From:*László Sándor <sandorl@gmail.com>

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