Disagreeing with the stat books

The typical statistics book states that to evaluate something, you state a goal, perform the experiment, and determine if the goal has been met. I believe this is also what the FDA expects. Whereas this sounds reasonable, the problem is that for many companies, not much time is spent on goals during development and evaluation of methods. The result is that after the evaluation is done, people will now start to ask what the goal should really be. But changing the goal after the evaluation is done is frowned upon.

For example, an assay precision goal is set at 5% CV and the result of the evaluation is 5.1% Say the team meets and decides 5.1% is acceptable and changes the goal to 6%. Is there something wrong with this? I say no. In my experience at Ciba Corning, this type of situation occurred periodically which led to the team discussing what we should do. The decision was always unanimous and sometimes favored the product being withheld (or recalled) and sometimes favored product release. Ideally, we should have had such discussions for each goal before the evaluations but it never happened.

Sometimes during the discussions, a “limited product release” was suggested. I always thought this was funny because every product release was limited by our manufacturing capacity so a “limited product release” really meant limited by as fast as you could make and ship product.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: