PVRC ☆ India, 20210423 10:35 (50 d 04:03 ago) Posting: # 22317 Views: 627 

Hi all, If an additional group is added to the study (due to recruitment issues) instead of four groups actually planned (4 x 4 Williams design), is it necessary to include the group effect in the statistical analysis plan ?? with best regards PV 
ElMaestro ★★★ Denmark, 20210423 12:17 (50 d 02:22 ago) @ PVRC Posting: # 22318 Views: 545 

Hi PVRC, » If an additional group is added to the study (due to recruitment issues) instead of four groups actually planned (4 x 4 Williams design), is it necessary to include the group effect in the statistical analysis plan ?? Good question. If this is a dossier for EU: 1. If you don't add a group effect, the regulator is likely to ask for it after submission. 2. If you do add a group effect, regulators are likely to ask you to submit a secondary analysis without it. At the end of the day Group is a betweenfactor, like sequence. Thus, the discussion is quite academic if we look at the confidence interval. Another matter of course is if we, for some reason or other, take an interest in the pvalue of the group effect itself or group x treatment. The latter sends shivers down my spine. — Pass or fail! ElMaestro 
Helmut ★★★ Vienna, Austria, 20210423 15:14 (49 d 23:24 ago) @ ElMaestro Posting: # 22322 Views: 538 

Hi ElMaestro & PVRC, » If this is a dossier for EU: » 1. If you don't add a group effect, the regulator is likely to ask for it after submission. Hundreds of studies accepted in the past without one. Seems to become increasingly fashionable recently. » 2. If you do add a group effect, regulators are likely to ask you to submit a secondary analysis without it. » Xactly. » At the end of the day Group is a betweenfactor, like sequence. Thus, the discussion is quite academic if we look at the confidence interval. Yep. » Another matter of course is if we, for some reason or other, take an interest in the pvalue of the group effect itself or group x treatment. The latter sends shivers down my spine. Not even the highest dose of Schützomycin would help. BTW, last month I endured a ‘Type A Meeting’ for an IND with the FDA. I proposed to use ‘Model II’ without the stupid pretest for a G × T interaction in ‘Model I’ because it inflates the Type I Error. Since writing a paper is on my todolist for more than five years (_{} Nastia; I’m still collecting data), I was referring to my presentation at BioBridges in Prague 2018 (see esp. the backupslides). Was accepted. — Diftor heh smusma 🖖 Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 
ElMaestro ★★★ Denmark, 20210423 12:27 (50 d 02:11 ago) @ PVRC Posting: # 22319 Views: 543 

By the way: » If an additional group is added to the study (due to recruitment issues) instead of four groups actually planned (4 x 4 Williams design), is it necessary to include the group effect in the statistical analysis plan ?? I am assuming you meant you had intended one group, but now have two. In your post your mentioned "instead of four groups" which did not compute for me if we talk dosing groups. But perhaps I got you wrong? — Pass or fail! ElMaestro 
PVRC ☆ India, 20210506 12:22 (37 d 02:16 ago) @ ElMaestro Posting: # 22337 Views: 341 

» I am assuming you meant you had intended one group, but now have two. In your post your mentioned "instead of four groups" which did not compute for me if we talk dosing groups. But perhaps I got you wrong? Hi Elmaestro, thank you for the reply, What i mean is 36 subjects were divided in to four groups for the study. However an additional group was added due to that the study not completed in four groups. I assume that this will not have an effect on the study? But would like to understand what is actually the group effect? thanks in advance.... PVRC 