How can a potential user distinguish between a quantitative model that may be of some real value and one that is not? The model builder rarely provides much help, since most are advocates of their own work and tend to lose their objectivity toward the model. Therefore, an independent evaluation...

COAL WAS DISCOVERED IN NIGERIA IN 1909 AND COAL MINING STARTED WITH A DRIFT MINE AT OGBETE, ENUGU IN 1915. SINCE 1958/59, WHEN COAL PRODUCTION REACHED ITS PEAK, THERE HAS BEEN A PERSISTENT FLUCTUATION IN THE AMOUNT OF COAL PRODUCED IN SUBSEQUENT YEARS. THIS PAPER THEREFORE INVESTIGATES THE MAJOR...