 - A decrease in AM or PM PEF below the Run-in Period stability limit on any 2 consecutive days before Baseline. At Visit 1, the Run-in Period stability limit for PEF will be established based on the subjects personal best. If the subject does not have a historical personal best, the historical PEF measurement will be the PEF predicted based on the subjects sex, age, and height. PEF value to be multiplied by 0.70 to determine stability limit. 