The paper “Less Air Pollution Leads to Rapid Reduction of Airway Inflammation and Improved Airway Function in Asthmatic Children” (Pediatrics [2009]: 1051–1058) describes a study in which children with mild asthma who live in a polluted urban environment were relocated to a less polluted rural environment for 7 days. Various measures of respiratory function were recorded first in the urban environment and then again after 7 days in the rural environment. The accompanying graphs show the urban and rural values for three of these measures: nasal eosinophils, exhaled FENO concentration, and peak expiratory flow (PEF). Urban and rural values for the same child are connected by a line. The authors of the paper used paired t tests to determine that there was a significant difference in the urban and rural means for each of these three measures. One of these tests resulted in a P-value less than .001, one resulted in a P-value between .001 and .01, and one resulted in a P-value between .01 and .05.
a. Which measure (Eosinophils, FENO, or PEF) do you think resulted in a test with the P-value that was less than .001? Explain your reasoning.
b. Which measure (Eosinophils, FENO, or PEF) do you think resulted in the test with the largest P-value? Explain your reasoning.