But by 1994 the Northeast states faced sanctions when computer models could not demonstrate that controls would yield attainment. The problem, they said, was ozone transport from outside the OTC region, so EPA organized the Ozone Transport Assessment Group, comprising the 37 states from North Dakota to Texas and eastward, to solve the problem. Others insisted the effect is nonexistent. The answer is that human activity does not emit ozone, so we can't track it directly. OTAG's transport research used modeling and statistical science, two very different approaches.
Statistical scientists take data for all episodes and look for patterns.
The modelers point out that attainment is a matter of extremes, not averages, so the statistical work is irrelevant. Modeling shows different episodes having different causes, so a given set of controls averaged over the modeled episodes tend to wash out. Modeling has produced a sea of numbers, but most modelers insist that only qualitative conclusions can be drawn. Advocates have taken the numbers they like and run with them publicly. Statistical analysis does not show cause and effect, as modeling sometimes does.