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

*To*: asreml@ram.chiswick.anprod.csiro.au*Subject*: Variance estimates*From*: Steve Miller <millers@wright.aps.uoguelph.ca>*Date*: Wed, 5 May 1999 17:15:42 -0500 (EDT)*Sender*: asreml-owner@ram.chiswick.anprod.csiro.au

I am trying to interpret some output from a variance component estimation attempt with asreml. I have run a random regression model for fat depth in beef cattle and I am modelling fat depth on weight. The .as file is Random regression of rib fat dpeth on weight animal 3220 !I #Animal bdate 731 !A # in format 22/07/69 etc sire 199 !A #example 'NBBK090' with the quotes breed 4 !A #!DHHHH !DMGMG !DSSSS #4 of these herd 23 !A # nut 8 !A #nutritional treatment imposed during grow out fin 2 !A #finish, pasture or feedlot mk1 3 !A #market, Domestic, Korean or Japanese mk2 2 !A #market, Domestic or Export cohort 12 !A #Taurus, steer, 1993, 1st intake TS931 dtwt #date of weight eg 34491 wt !-422.5 !/237.5 #weight in kg standardized to -1 to 1 dtp8 !M-1 #date of p8 fat measure p8 !M-1 !*100 #p8 fat measure (mm) dtrib !M-1 #date of rib measure rib !M-1 !*100 #rib fat 12/13 measure (mm) dtema !M-1 #date of eye-muscle area measure (sqcm) ema !M-1 #eye muscle area measure (sqcm) bdate2 !M25406 #birth date in days like dtrib etc above cg 41 !A #cohort.fin.mk2 n2 28 !A #cohort.nut ../../../Data/data4.dat !maxit 1000 # reading data file rib ~ mu wt wt.wt cg cg.wt cg.wt.wt n2 n2.wt n2.wt.wt, br br.wt br.wt.wt !r he he.wt s s.wt an an.wt 1 2 3 !STEP 0.1 2547 3 0 DIAG 9804.57 9761.96 9214.61 !GUUU he 2 2 0 US 4702.17 4214.69 5946.26 !GUUU he s 2 2 0 US 4702.17 4214.69 5946.26 !GUUU s an 2 2 0 US 17854 18000 46610 !GUUU an The output for my variance components is Source Model terms Gamma Component Compnt/StndErr Residual DIAG=Dia 1 328.423 9805.47 25.01 Residual DIAG=Dia 2 326.861 9758.85 25.16 Residual DIAG=Dia 3 308.629 9214.49 24.81 sire US=UnStr 1 157.896 4714.19 7.31 sire US=UnStr 1 142.277 4247.86 5.86 sire US=UnStr 2 201.654 6020.64 5.98 animal US=UnStr 1 583.459 17419.9 29.40 animal US=UnStr 1 771.300 23028.1 29.85 animal US=UnStr 2 867.785 25908.8 19.29 'Component' are the variance components I am interested in. What are the 'Gamma' components and how sould I be using these? I have three residuals.. the data is sorted by weight. So there will be three residuals, one for each of three weight classes. Also I have a problem that if I expand out the variances over the range of weights, in this case from -1 to 1 for the standardized weights some are negative... or sometimes the correlation between measures at different weights could be greater than 1. How can I constrain the acceptable solutions to consider the parameter space where variances are not neagtive for example. Take the component for animal above ... the variance at weight -1 would be 17419.9 - 2 * 23028.1 + 25908.8 = -2727.5. This is a negative variance... the problem exists in this case at the low weights. I saw in the manual that placing some constraints on a function of the variance components is possible. However, I can't see how to make it work for my example. Hopefully someone out there can be of some help. The problem appears to be for my animal or permanent environmental effects. I have three measures per animal. Steve Miller -- Asreml mailinglist archive: http://www.chiswick.anprod.csiro.au/lists/asreml

**Follow-Ups**:**Re: Variance estimates***From:*bsouthey@iastate.edu

- Prev by Date:
**Re: ASREML with Digital or f77 compilers** - Next by Date:
**Re: Variance estimates** - Prev by thread:
**Re: ASREML with Digital or f77 compilers** - Next by thread:
**Re: Variance estimates** - Index(es):