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From |
"alessia matano" <alexis.rtd@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: interaction between continuous variables |

Date |
Tue, 4 Sep 2007 18:34:11 +0200 |

Hi, I am trying to perform a regression trying to put an interaction term between two continuous variables. In a first attempt I discretize one of them and then multiply the relative dummy with the other variable, and I obtained some interesting effect. Then I red that this is not correct to be done and it is also arbitrary (because I decide how descretize one variable...I was calcultaing some threshold using the percentiles say p(33) p(66)) getting three values. Therefore I red some papers saying that you should centered the continuous variables (becuase of problem of multicollinearity: is that correct?) and then simply multiply them. In this way results are not so interesting anymore. The main and interacted variables together are never significant and it happens (and here I would like your help) that in one case only the interacted is significant while the main effect is not. Whta does it mean? Can someone help me. Thanks alessia * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: interaction between continuous variables***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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