[...] Informal learning systems may increase overall performance but these cannot be exactly measured nor quantified. But then, neither can successful business practices or military strategy be exactly defined. Good business and military leaders know that success is a blend of science and art. I see informal learning as a similar endeavour. There are ways of measuring effectiveness - see Estimating the Performance Situation - and evaluation needs to be directly linked to your analysis. For example, morale cannot be quantified, but you know when good morale exists or when it is missing in an organisation. …