## F2 (similarity factor): An arithmetic skill-test – not a widget for quality assessment of pharmaceuticals

While surfing the internet, I found a prize Claim Form from Tim Hortons (Coffee Shop), which requires the winners to complete a skill test, a simple arithmetic exercise, to claim the prize (link). The exercise goes like this: multiply 2×4, add 8, subtract 4, add 6 and then show the correct answer. The exercise is unrelated to the quality or value of the prize, but a requirement for receiving the prize.

It reminds me of F2 (similarity factor) requirement, which is a very similar arithmetic exercise as well, with added parameters of taking logarithm and square root of numbers to come up with an answer to receive the “prize” of “regulatory compliance”, i.e. regulatory approval of your product (usually tablet/capsule) as bioequivalent with or without a human bioequivalence study. The point being, the skill test, in this case “similarity factor” unrelated to the product quality (scientifically, statistically or otherwise) and/or lack relevance to human bioequivalence study, but is required to meet a compliance requirement (link).

BTW, if you would be using a scientific calculator or computer spreadsheet for the calculations, then you might also be required “validation” of the calculator and spreadsheet software, and its use, to confirm if they or you are performing proper calculations for which one might require help of a CSV (Computer Software Validation) expert or consultant.

Just a thought in case you are considering using F2 (similarity factor) for your studies or product evaluation for regulatory compliance – otherwise you do not have to worry about this factor as this is pretty much useless exercise unrelated to quality aspect of the pharmaceutical products.