Bioequivalence and Bioavailability Forum

Dear all,

Which type of randomization is best for a 2 x 2 crossover design?
(I think block randomization is good)

If my study needs total 26 subjects, how many subjects I want to take as additional subjects? 26+2 or 26+4?

Is there any special rule for calculating the number of aditional subjects?

If I use block randomization, what is the best block size? 2 or 4? why?

In the randomization procedure, Is it necessery to generate separate randomization codes for total subjects (26) and seperate codes for additional subjects (2 or 4)? (by using different seed number in SAS pgm).

or is it possible to generate one randomization code by using one seed number for (26+2) or (26+4) subjects?

When we use this addtional subjects in the analysis?

In the case of block randomization, is there any difference in the result of analysis (90 % C.I and ANOVA table) if I use the following two methods
(1) the blocks are selected randomly and the subjects in each blocks are also selected randomly. (using the statement block random subject random in the proc PLAN of SAS pgm)
(2) the blocks are selected orderly and only the subjects in each block are randomly selected. (using the statement block order subject random in proc PLAN

Thanks

Mathews