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From |
Michael Morrison <Morrimic@niacc.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Logistic regression interpretation - continued questions with ONY binary predictors |

Date |
Wed, 22 Sep 2010 09:38:56 -0500 |

Hi Bill,

Mike On 9/21/2010 6:24 PM, Dr. Bill Westman wrote:

Mike. Thanks. It seems that this book and others move to models that are seem to be unrelated to a binary outcome and two binary predictors (specifically). With a second binary predictor, many of the techniques suggested by Long& Freese seem irrelevant. There isn't really a "mean" risk - it is either High or NOT. The fact that I do not have any continuous predictors makes this case easier -- I think, but still perplexing to me. If any listers have insight, please let me know On Tue, Sep 21, 2010 at 3:04 PM, Michael Morrison<Morrimic@niacc.edu> wrote:I recommend you read Long& Freese (2006) /Regression Models for Categorical Dependent Variables Using Stata. It provides interpretation of odds, _controlling for covariates_ and ways to test your model's goodness of fit. Also of interest is their Spost commands. Mike / On 9/21/2010 4:36 PM, Dr. Bill Westman wrote:Dear Listers: I have more of a stats question than a stata question, but here goes: A simple logistic regression was run - outcome - Survived/Non Survived (1/0), with Group(Treatmeant/Control -- 1/0)& Risk(High/Low -- 1/0) The results ------------------------------------------------------------------------------ Survived | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- Risk | 4.790295 2.589136 2.90 0.004 1.660699 13.81763 group | 2.111181 .9107981 1.73 0.083 .9063649 4.917538 ------------------------------------------------------------------------------ Assuming the .10 level of significance was acceptable (for discussion purposes) Can I assume that odds of treatment survival were 2.1 times higher in the treatment Group for LOW risk patients? And for High Risk patients in the treatment group is the adds 4. 8 + 2.1 (or 6 times higher)? Other than test for interactions, can I run a graphs of these two groups? Can I estimate the "average" effect of Treatment across both high and low risk patients? If so, how? What other tests might I wish to do in Stata? Thanks Bill * * 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: Logistic regression interpretation - continued questions with ONY binary predictors***From:*"Dr. Bill Westman" <webicky@gmail.com>

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