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From |
Jana von Stein <janavs@umich.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Presenting Interaction in LR |

Date |
Thu, 8 Dec 2011 16:47:26 -0500 |

Consider some of the resources here: https://files.nyu.edu/mrg217/public/interaction.html Jana On Dec 8, 2011, at 2:35 PM, Cameron McIntosh wrote:

I would also suggest looking at the following for additionalguidance on how to examine and discuss your interaction effects:Hayes, A.F., & Matthes, J. (2009). Computational procedures forprobing interactions in OLS and logistic regression: SPSS and SASimplementations. Behavior Research Methods, 41, 924-936. http://www.personal.psu.edu/jxb14/M554/articles/Hayes&Matthes2009.pdfAguinis, H, & Gottfredson, R. K. (2010). Best-practicerecommendations for estimating interaction effects using moderatedmultiple regression. Journal of Organizational Behavior, 31, 776-786.http://mypage.iu.edu/~haguinis/JOB2010.pdfShieh, G. (2011). Clarifying the role of mean centering inmulticollinearity of interaction effects. British Journal ofMathematical and Statistical Psychology, 64(3), 462–477.Francoeur, R.B. (2011). Interpreting interactions of ordinal orcontinuous variables in moderated regression using the zero slopecomparison: tutorial, new extensions, and cancer symptomapplications.International Journal of Society Systems Science,3(1/2), 137-158.Cam ----------------------------------------Date: Thu, 8 Dec 2011 18:57:29 +0100 Subject: Re: st: Presenting Interaction in LR From: maartenlbuis@gmail.com To: statalist@hsphsun2.harvard.edu On Thu, Dec 8, 2011 at 6:25 PM, Campo, Marc wrote:We are running a Linear Regression model where we are interestedin the effect of a dichotomous predictor (GROUP) on a ratio levelrehabilitation outcome scale. It is a pre/post situation where wehave adjusted for baseline values (BASELINE) of the scale. Thereis an interaction between GROUP and BASELINE. People at the lowend of the scale do better in one group and at the higher end dobetter in the other (but not much of a difference in clinicalterms).I was going to present the coefficients for GROUP at varyingvalues of baseline. BASELINE however, is somewhat skewed and sowhen I calculate the coefficient for group at the mean and 1SDabove and below the mean BASELINE value we end up with a lowercoefficient that is fairly close to the minimum value. Are thereother choices? 25, 50, 75Th percentiles? Graphs instead? I don'tthink transforming BASELINE adds enough to be worth the complexityand the relationship is fairly linear as is..Quartiles sound fine to me, but the most important thing is that the values make some substantive sense. There often are some values on a scale that are especially meaningful, e.g. 12 and 16 years of education in the American educational system (high school and college degree). In that case I would use those values. 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/

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**References**:**st: Presenting Interaction in LR***From:*"Campo, Marc" <MCampo@mercy.edu>

**Re: st: Presenting Interaction in LR***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: st: Presenting Interaction in LR***From:*Cameron McIntosh <cnm100@hotmail.com>

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