This is a pre-copyedited, author-produced PDF of an article accepted for publication in Biometrika following peer review. The version of record is available online at: https://academic.oup.com/biomet/article/99/1/151/252316.
Except where otherwise noted, this item's license is described as This is a pre-copyedited, author-produced PDF of an article accepted for publication in Biometrika following peer review. The version of record is available online at: https://academic.oup.com/biomet/article/99/1/151/252316.