It is strange, then, that Limits to Growth provided such an outcry, but Mankind at the Turning Point didn't. In the literature there are essentially two kinds of tests of the world models. One is to vary, within presumably plausible ranges, the parameter values to see whether the results remain essentially the same or whether those plausible changes lead to drastically different outcomes. The other is either to run the model backward from its starting point to see whether it can correctly retrodict or to start it in the past and run it up to the present. In authors opinion, the greatest use for these models and their successors lies not with all-encompassing world models, but with the analysis of problems of more limited scope; recall those reports from Egypt, Iran, Venezuela, and West Germany with their much more localized applications.