a region of several hundreds of square miles. Even with unlimited funding, 

 exact evaluation of an experiment is not possible. In the case of operational 

 weather modifications, there are economic limits to the instrumentation 

 that can be afforded. Therefore, decisions regarding operation must be 

 made with only part of the data at hand. Whether the missing data are 

 of serious consequences depend upon the specific circumstances. If opera- 

 tional weather modification is to be more generally applied, the decision 

 making apparatus for determining when and how to permit operations 

 needs to be improved. 



Therefore, NACOA wishes to emphasize need to integrate statistical 

 and other analytical approaches (mostly computer modeling) to reduce 

 the uncertainty in evaluating the efficacy of weather modification. 

 NACOA urges all agencies that sponsor research and development in 

 weather modification, and all those who conduct operations, to explore 

 and utilize both statistical and nonstatistical techniques and to conduct 

 studies designed to bring these approaches together. 



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