The Half Full/Half Empty Syndrome
The 80/20 Rule (Pareto Principle), aka the law of the vital few and principle of factory sparsity, provides that for many events, roughly 80% of the effects come from 20% of the causes (metaphysical=cause and effect).
The principle is named after Italian economist Vilfredo Pareto, who, while at the University of Lausanne in 1896, published his first paper "Cours d'économie politque." He showed that approximately 80% of the land of Italy was owned by 20% of the population; he essentially developed the principle by observing that 20% of the peapods in his garden contained 80% of the peas; (watch out for those "peas in a pod", i.e. cliques).
The Comfort Zone: