The Chestnut and Rowe study did not measure values for visibility improvement in Class I areas outside the three regions.
Values for visibility improvement in Class 1 areas outside the three regions were not studied by Chestnut and Rowe. 
mnli hypothesis: Values for visibility improvement in Class 1 areas outside the three regions were not studied by Chestnut and Rowe.  premise: The Chestnut and Rowe study did not measure values for visibility improvement in Class I areas outside the three regions.