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question regarding output using lme4

Ben Bolker
On 14-01-11 09:23 AM, Elin Renborg wrote:
Your problem is that you have inadvertently specified the 'sire' and
'dam' random effects twice; since (1 | sire/salt) (for example) expands
to (1|sire) + (1|sire:salt) (where sire:salt indicates an *interaction*
between sire and salt),  (1 | sire ) + (1 |sire/salt) expands to (1 |
sire) + (1| sire) + (1|sire:salt).

  It would be nice if we could (1) automatically detect and
collapse/drop redundant terms; (2) do a better job warning on redundant
terms, but so far we can't.

  The solution is simply to use (1|sire/salt) + (1|dam/salt), leaving
out the (1|sire) and (1|dam) terms.
If you look at the variance estimates here, and just focus on the orders
of magnitude, you'll see that both 'dam' terms (dam and dam.1) are tiny,
and one of the sire terms is much smaller than the

 Groups    Name        Variance  Std.Dev.
 salt.dam  (Intercept) 1.073e-03 3.275e-02
 salt.sire (Intercept) 5.051e-05 7.107e-03
 dam       (Intercept) 2.313e-19 4.810e-10
 sire      (Intercept) 1.943e-10 1.394e-05
 dam.1     (Intercept) 2.249e-18 1.500e-09
 sire.1    (Intercept) 7.323e-05 8.558e-03
 Residual              6.299e-03 7.936e-02

Thread (2 messages)

Elin Renborg question regarding output using lme4 Jan 11 Ben Bolker question regarding output using lme4 Jan 11