how about randomly selected block sizes? [R for BE/BA]

posted by ElMaestro  – Belgium?, 2019-08-28 07:26  – Posting: # 20526
Views: 1,035

Hi yjlee168,

» The block size in package randomizeBE is fixed and its deafult is set to 2*number of sequences. Is it better to set the blocksize as randomly selected as suggested in this article?
»
» » ...RTFM

If blocksize is missing it defaults to 2*number of sequences.



I did not know of that paper or this kind of thinking - thank you for enlightening me.
I think the paper addresses bias through predictability. Imagine we have TR/RT and block size 4, and that you can tell the treatments apart though the study is supposed to be blind.
If you dose subject 1 and 2 in a given period with T then you can tell with certainty that the other two in the block will be given R.
BE trials tend to be open label. By this thinking the block size phenomenon would not affect the outcome or have the potential to bias it.

Noone says blocks are necessary at all. For trials at single centers in single groups, which acccount for the majority of BE trials, I don't see any particular need for blocks.

I could be wrong, but...
Best regards,
ElMaestro

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