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From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: FW: st: Plotting several linear associations in one graph for comparison |

Date |
Mon, 16 Jul 2012 16:48:06 +0200 |

On Mon, Jul 16, 2012 at 4:10 PM, Amal Khanolkar wrote: > - I understand the need for the replace commands. But as above, I think I introduce bias by narrowing the study population down to a very small proportion of the true study population. I tried choosing for example, mean BMI, and height, and the largest category of maternal education with most number of subjects. Most of my subjects are aged 18 (around 90% of them), but restricting it to just one birth year, means I loose most of the population. Is it possible in my example above to select select a range of birth years (all birth years for example, from 1973 to 2008), maybe include more maternal educational categories?? I could then obtain a graph for a study population with greater variation right? Bias means that you do not measure what you want to measure. As a consequence, no estimate can be biased per se, i.e. without specifying what the estimate should be an estimate of. In this case I do not think your predictions are biased (assuming your model is ok): they measure the predicted blood pressure for the specific group you chose. The problem you are facing is that with 8 covariates your regression model is a plane in 9 dimensional space, which is virtually impossible to visualize in one go. (I have heard certain mushrooms can help, but I have not tried it myself and I would not recommend their use.) The trick is not to try to visualize the entire model in one go, but to look at different "slices". You have looked at BP by motherland and birth weight, you can now create a different graph that fixes birth weight and varies birth year, and another graph that varies BMI, etc.. -- 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/

**Follow-Ups**:**Re: FW: st: Plotting several linear associations in one graph for comparison***From:*Maarten Buis <maartenlbuis@gmail.com>

**References**:**st: Plotting several linear associations in one graph for comparison***From:*Amal Khanolkar <Amal.Khanolkar@ki.se>

**Re: st: Plotting several linear associations in one graph for comparison***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: st: Plotting several linear associations in one graph for comparison***From:*Amal Khanolkar <Amal.Khanolkar@ki.se>

**FW: st: Plotting several linear associations in one graph for comparison***From:*Amal Khanolkar <Amal.Khanolkar@ki.se>

**Re: FW: st: Plotting several linear associations in one graph for comparison***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: FW: st: Plotting several linear associations in one graph for comparison***From:*Amal Khanolkar <Amal.Khanolkar@ki.se>

**Re: FW: st: Plotting several linear associations in one graph for comparison***From:*Maarten Buis <maartenlbuis@gmail.com>

**RE: FW: st: Plotting several linear associations in one graph for comparison***From:*Amal Khanolkar <Amal.Khanolkar@ki.se>

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