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From |
Steven Samuels <sjhsamuels@earthlink.net> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: re:linear regression with robust variance estimation |

Date |
Sun, 8 Feb 2009 11:48:39 -0500 |

Shehzad-

A few suggestions:

-Steve On Feb 6, 2009, at 9:28 AM, Nick Cox wrote:

I don't know how much help this would be statistically, or scientifically, but in such cases I would always have a quick look at second baby - first baby perhaps plotted against their mean. If babies are better logged or otherwise transformed, that's a further wrinkle. Nick n.j.cox@durham.ac.uk Kit Baum Ali said I have a small data set of 136 infants each 2 of them have the same mother. All mothers have a disease which I am at its effect on birthweight. These women were diagnosed and treated after giving birth for the first child. I am trying to measure the difference in mean birthweight between infants who were born before treatment and those who were born after treatment. At the same time I want to account for parity (3 categories 1, 2 or 3) and gestational age (4 categories). I am using regress with robust option to account for the fact that the data is not independent. Is there a way to include the mothers personal number in the model? Or does robust take into this problem into account? The model I used is x: regress birthweight i.disease i.parity i.gestationalage, robust why not cluster(motherid) ? That subsumes robust and allows for error correlation among children of the same mother. * * 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**:**st: re:linear regression with robust variance estimation***From:*Kit Baum <baum@bc.edu>

**st: RE: re:linear regression with robust variance estimation***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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