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From |
"Leny Mathew" <lenymathewc@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: GLLAMM error: log-likelihood cannot be computed |

Date |
Mon, 8 Oct 2007 16:40:52 -0400 |

That's a good idea. Fortunately for me, there is no one with a 1.0 in any of the hormones at any of the three time points. On 10/8/07, Nick Cox <n.j.cox@durham.ac.uk> wrote: > But I think the least unsatisfactory options > are > > 1. To omit zeros and to indicate them by a rug of ticks > on the other axis. > > 2. To plot downward-pointing arrows at say > log(0.5). Whatever constant is used should > be less than the smallest positive value observed. > > Nick > n.j.cox@durham.ac.uk > > > -----Original Message----- > > From: owner-statalist@hsphsun2.harvard.edu > > [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Nick Cox > > Sent: 08 October 2007 21:09 > > To: statalist@hsphsun2.harvard.edu > > Subject: RE: st: RE: GLLAMM error: log-likelihood cannot be computed > > > > > > So, a log of 0 sometimes means that the data are 1 > > and sometimes that they are 0? > > > > There's no neat solution to this one. > > > > Nick > > n.j.cox@durham.ac.uk > > > > Leny Mathew > > > > > Thanks Nick. For the purposes of the graph, I created a new variable > > > with the zeros changed to 1 and then took the log; > > effectively setting > > > them as zero in the log graph. I guess I could scale the > > variable by a > > > very small value and then take the log also. > > > > > > On 10/8/07, Nick Cox <n.j.cox@durham.ac.uk> wrote: > > > > -gllamm- I leave to experts on it. > > > > > > > > -glm- produces predictions on the scale of the response, > > > > whatever the link. It can also be quite sensible to use a > > > > log scale for subsequent graphing. Indeed I've found > > > > log link and log scale for graphs invaluable in some cases. > > > > The results are not equivalent to transforming the response > > > > because the log of the mean is not in general the mean > > > > of the logs (and similarly for any nonlinear transformation). > > > > > > > > However, you can't show zeros on a log scale. If you > > > > try this, Stata just gives you a dopey graph. That's > > > > its way of saying "Isn't that rather a silly thing > > > > to ask for?" > > * > * 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/ > * * 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/

**References**:**RE: st: RE: GLLAMM error: log-likelihood cannot be computed***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**RE: st: RE: GLLAMM error: log-likelihood cannot be computed***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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