There can be measurement error related to the procedure to collect the complaints imprecision in the indicator as a measure of product quality (is it a trivial or serious complaint? In a given time period, do you have more challenging customers who complain, that does not reflect a change in product quality?). But in this example alone there can be many elements of uncertainty. For instance, a typical measure of service quality may be ‘the # of customer complaints/time period’. In our world, it is common to translate imprecise and vague notions around performance and impact to a set of numerically crisp values, giving us a false notion of precision and validity. We are experts at turning grey into black and white Where does uncertainty lurk in our work, and what can we do to better take it into account? This limited treatment produces a misplaced concreteness in what we do and reduces its usefulness. Still, we acknowledge it in a fairly limited way, and dealing with it explicitly is relatively rare. While this quote emerged from the context of linking the government of Iraq with weapons of mass destruction, uncertainty (everything but the known knowns) pervades the world of evaluation, social impact assessment and performance measurement. This infamous quote left some people befuddled, others impressed. But there are also unknown unknowns - there are things we do not know we don't know.' There are known unknowns that is to say, there are things that we now know we don't know. 'There are known knowns there are things we know that we know.

Known unknowns