Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
From | Richard Williams <richardwilliams.ndu@gmail.com> |
To | statalist@hsphsun2.harvard.edu, statalist@hsphsun2.harvard.edu |
Subject | Re: st: Nominal or ordinal? |
Date | Thu, 12 Aug 2010 17:55:49 -0500 |
use "http://www.indiana.edu/~jslsoc/stata/spex_data/ordwarm2.dta";, clear tab1 warm reg warm yr89 male white age ed prst rvfplot That plot certainly doesn't look like a random scatter of points.Having said that, if the ordinal variable is independent rather than dependent, it is pretty easy to test whether it is ok to treat it as continuous. Long and Freese (in the 2006 book available from Stata Press that I referenced earlier) show how in Ch. 9 of their book. Basically, you run a model where the variable is treated as continuous and another model where you break the variable up into dummies. If breaking up into dummies does not significantly improve fit you can treat the variable as continuous.
At 04:26 PM 8/12/2010, Michael N. Mitchell wrote:
Dear Dave (and all others)I know I am personally rather trusting of treating such scales as interval data... do you or any others have suggestions on references justifying the treatment of scales like this as interval?Many thanks, 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 2010-08-12 1.29 PM, David Bell wrote:-- Chelsea,Most of the world is willing to treat scales like this as interval data. Sure it isn't "exactly" interval. Be sure to consider whether your audience will be familiar with interpretations of ordinal logit regressions.Dave ==================================== David C. Bell Professor of Sociology Indiana University Purdue University Indianapolis (IUPUI) (317) 278-1336 ==================================== On Aug 12, 2010, at 2:59 PM, Polis, Chelsea B. wrote:Dear Statalisters,I am working with a dependent variable that has the following four potential responses: (1) Not Likely, (2) Slightly Likely,(3) Quite Likely, (4) Extremely Likely.A colleague thinks this is an ordinal variable which should be analyzed using ordered logit regression. My sense was that this is a nominal variable, and should be analyzed using multinomial regression - since we cannot know if the levels areequally spaced in people's minds.My apologies for what is probably a very simplistic question, but I've searched Statalist and online, and I still am notentirely certain. I would greatly appreciate input on this question. Thanks, Chelsea * * 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/
------------------------------------------- Richard Williams, Notre Dame Dept of Sociology OFFICE: (574)631-6668, (574)631-6463 HOME: (574)289-5227 EMAIL: Richard.A.Williams.5@ND.Edu WWW: http://www.nd.edu/~rwilliam * * 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/