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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: age: factor variables may not contain noninteger values |

Date |
Tue, 8 Nov 2011 19:57:38 +0000 |

I agree, naturally; it's perhaps a question of whether other studies in your field would use the same recipe. Nick On Tue, Nov 8, 2011 at 7:47 PM, Lars Folkestad <lfolkestad@health.sdu.dk> wrote: > Thats true but biologically when i'm 39years and 10 months i'm closer to > 40 than 39. > Im not sure it makes a difference but it might - floor may potentially > underestimate the effect of age. > > lars > > Den 08/11/11 20.39 skrev "Nick Cox" <njcoxstata@gmail.com>: > >>All that said, as age as an integer usually means "age last birthday", >>I am surprised that -round()- is regarded as the answer. I would put >>my foot down for -floor()-. >> >>For example, I am 19 and will not be 20 until next birthday. >> >>Nick >> >>On Tue, Nov 8, 2011 at 7:29 PM, Lars Folkestad <lfolkestad@health.sdu.dk> >>wrote: >>> Thank you for that jesper. It sure did the trick. >>> lars >>> >>> Den 08/11/11 13.17 skrev "Jesper Lindhardsen" <JESLIN01@geh.regionh.dk>: >>> >>>>Hi Lars, >>>> >>>>Try >>>> >>>> >>>>g new_age= round(age_var,1) >>>> >>>> >>>>HTH, >>>> >>>>Jesper >>>> >>>>-----Original Message----- >>>>From: owner-statalist@hsphsun2.harvard.edu >>>>[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Lars >>>>Folkestad >>>>Sent: 08 November 2011 12:14 >>>>To: statalist@hsphsun2.harvard.edu >>>>Subject: Re: st: age: factor variables may not contain noninteger values >>>> >>>>This helps a lot. >>>>Thank you. >>>> >>>>But i have a question about the second point. >>>>Is there a quick and easy way to round the age to the nearest integer >>>>value? I could use the floor / ceil functions, but some of the ages >>>>Should be rounded up and some should be rounded down. >>>> >>>>lars >>>> >>>>Den 08/11/11 11.40 skrev "Maarten Buis" <maartenlbuis@gmail.com>: >>>> >>>>>On Tue, Nov 8, 2011 at 11:13 AM, Lars Folkestad wrote: >>>>>> I am trying to investigate the interactions between age and a >>>>grouping >>>>>>variable in a regression model, using this code: >>>>>> >>>>>> xi: regress Var1 age##i.group >>>>>> >>>>>> Var1: is a continuous variable >>>>>> Age: is a continous variable / float >>>>>> >>>>>> When i run the code i get the following error message: >>>>>> age: factor variables may not contain noninteger values >>>>> >>>>>First, you are mixing -xi- and factor variable notation. You should >>>>>just leave the -xi:- prefix away. >>>>> >>>>>Second, in most surveys I am aware of age will be measured in whole >>>>>years. In those cases age should only contain integer values and this >>>>>error message means I made an error while preparing the data. This is >>>>>true regardless of how the data is stored. However, this is not >>>>>necessarily an error, you could have fractional age if you had for >>>>>instance exact birth dates and exact dates at which events of interest >>>>>happen. Alternatively, I may have standardized age or rescaled it so >>>>>it is measured in decades rather than years. However, in the latter >>>>>two cases I would have created new with different variable names >>>>>(probably z_age and age_d). So I would check whether non-integer age >>>>>would make sense given the way your data was collected. >>>>> >>>>>Third, whether there is an error or not you probably want -regress >>>>>var1 c.age##i.group- i.e. tread age as a continuous variable and not >>>>>as a set of dummies. >>>>> >>>>>Hope this helps, >>>>>Maarten >>>>> >>>>>-------------------------- >>>>>Maarten L. Buis >>>>>Institut fuer Soziologie >>>>>Universitaet Tuebingen >>>>>Wilhelmstrasse 36 >>>>>72074 Tuebingen >>>>>Germany >>>>> >>>>> >>>>>http://www.maartenbuis.nl >>>>>-------------------------- >>>>> >>>>>* >>>>>* 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/ >>> >> >>* >>* 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**:**Re: st: age: factor variables may not contain noninteger values***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: age: factor variables may not contain noninteger values***From:*Lars Folkestad <lfolkestad@health.sdu.dk>

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