In section 7.4.1, {lme4}'s random effects formula syntax is given as an example of the problem and it is shown how it fails with model.matrix(). However, this example is never completed and the "solution" switches to a different example from {survival}. I recommend completing the {lme4} example by showing its solution in {workflows}. The {survival} example is a good one too, but it feels jarring as a reader to start one example and then switch to a different example without completing the first.
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In section 7.4.1, {lme4}'s random effects formula syntax is given as an example of the problem and it is shown how it fails with
model.matrix()
. However, this example is never completed and the "solution" switches to a different example from {survival}. I recommend completing the {lme4} example by showing its solution in {workflows}. The {survival} example is a good one too, but it feels jarring as a reader to start one example and then switch to a different example without completing the first.