>but a proper analysis will divide the issue between now and 5 years from now and come up with requirements that fill the gaps The issue with the Waterfall mod

>but a proper analysis will divide the issue between now and 5 years from now and come up with requirements that fill the gaps The issue with the Waterfall model is that this approach doesn't work. Aiming for "now" means you come out with an outdated product in the future. Aiming for "5 years from now" means speculating on what users will eventually want, which is very error-prone. Trying to adjust course midway through is a nightmare - and completely defeats the point of trying to get requirements "right" the first time. >You can of course empirically interact, by wearing the user hat. This is not empirical: it does not involve observation or measurement of the real world. Speculating about user behaviour is no substitute for concrete data about how users actually behave.