[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: Kim Bunter <kbunter@metz.une.edu.au>, asreml@ram.chiswick.anprod.csiro.au*Subject*: Re: About !GP bending of US matrix*From*: bsouthey@iastate.edu*Date*: Tue, 30 Mar 1999 08:33:00 CST*In-reply-to*: Your message of "Tue, 30 Mar 1999 10:42:44 +1000." <3.0.6.32.19990330104244.007ab220@metz.une.edu.au>*Sender*: asreml-owner@ram.chiswick.anprod.csiro.au

Hi, There are a number of issues with regards to standard errors. Assuming the model is correct, probably the most important is that under maximum likelihood estimation these are the obtained from the Information matrix AND are asymptotic! This brings TWO issues: 1) Relationship between the AI matrix and the Information matrix as they are not the same. 2) What is meant by asymptotic? I.E. when is N large enough? Variance components are usually skewed and one can only guess about any ratios. Also, standard errors are usually a function of the true value of the estimate and the standard errors for ratios are usually based on Taylor series approximations - usually first order (correct me if I am wrong). With your estimates Kim, are the correlations actually different (0.91 is 1 standard deviation of 0.83 +-0.08)? Without knowing the data structure, traits and the estimated variance components, it is hard to draw any conclusions about the results. You may have a part-whole relationship between variables. Further, you clearly have more statistical information about one of the traits than the others and it probably has a higher heritability as well. Bayesian would overcome some (all) of the problems as the posterior would tell you considerable amount of information. But introduce other issues e.g proving that you have converged if using MCMC,... Regards Bruce Southey -- Asreml mailinglist archive: http://www.chiswick.anprod.csiro.au/lists/asreml

**Follow-Ups**:**Re: About !GP bending of US matrix***From:*Kim Bunter <kbunter@metz.une.edu.au>

**References**:**Re: About !GP bending of US matrix***From:*Kim Bunter <kbunter@metz.une.edu.au>

- Prev by Date:
**Re: About !GP bending of US matrix** - Next by Date:
**Re: About !GP bending of US matrix** - Prev by thread:
**Re: About !GP bending of US matrix** - Next by thread:
**Re: About !GP bending of US matrix** - Index(es):