As before (Section 3.4), each variance component in the output of the `REML`

statement is accompanied by an SE: for example, the variation among breeding lines is estimated to be ± 6242. This SE provides an indication of the precision with which the variance component is estimated. It may also provide a tentative indication of whether any variation is really accounted for by the term under consideration: that is, whether the null hypothesis

can be rejected. If *H*_{0} is true, the ratio

is expected to have a value of about ±1, on average. In the present case,

This is considerably larger than the expected value, suggesting that *H*_{0} is false.

If were an observation of a normally distributed variable, this ratio could be made the basis for a formal significance test. *z* would then be approximately an observation of a *standard normal variable*: that is, of a variable *Z* such that

(For an account of the normal ...

Start Free Trial

No credit card required