eprintid: 10083383 rev_number: 19 eprint_status: archive userid: 608 dir: disk0/10/08/33/83 datestamp: 2019-10-15 10:13:30 lastmod: 2021-12-29 23:25:40 status_changed: 2019-10-15 10:13:30 type: article metadata_visibility: show creators_name: Godolphin, PJ creators_name: Godolphin, EJ title: Robustness of crossover trials against subject drop-out - Examples of perpetually connected designs ispublished: pub divisions: UCL divisions: B02 divisions: D65 divisions: J38 keywords: Crossover design, subject drop-out, missing data, clinical trial, uniformly balanced repeated measurement design, perpetually connected note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: When performing a repeated measures experiment, such as a clinical trial, there is a risk of subject drop-out during the experiment. If one or more subjects leave the study prematurely, a situation could arise where the eventual design is disconnected, implying that very few treatment contrasts for both direct effects and carryover effects are estimable. This paper aims to identify experimental conditions where this problem with the eventual design can be avoided. It is shown that in the class of uniformly balanced repeated measurement designs consisting of two or more Latin squares, there are planned designs with the following useful property. Provided that all subjects have completed the first two periods of study, such a design will not be replaced by a disconnected eventual design due to drop-out, irrespective of the type of drop-out behaviour that may occur. Designs with this property are referred to as perpetually connected. These experimental conditions are identified and examined in the paper and an example of at least one perpetually connected uniformly balanced repeated measurement design is given in each case. The results improve upon previous contributions in the literature that have been confined largely to cases in which drop-out occurs only in the final periods of study. date: 2019-03-01 date_type: published publisher: SAGE PUBLICATIONS LTD official_url: https://doi.org/10.1177/0962280217736541 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1697190 doi: 10.1177/0962280217736541 lyricists_name: Godolphin, Peter lyricists_id: PGODO03 actors_name: Godolphin, Peter actors_id: PGODO03 actors_role: owner full_text_status: public publication: Statistical Methods in Medical Research volume: 28 number: 3 pagerange: 788-800 pages: 13 issn: 1477-0334 citation: Godolphin, PJ; Godolphin, EJ; (2019) Robustness of crossover trials against subject drop-out - Examples of perpetually connected designs. Statistical Methods in Medical Research , 28 (3) pp. 788-800. 10.1177/0962280217736541 <https://doi.org/10.1177/0962280217736541>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10083383/1/robustness-crossover-trials_FINAL.pdf