Statistical Analysis
The goal of the analyses was to examine the association
between long-term improvements in ambient
air quality and lung-function development in
children from 11 to 15 years of age, measured as
the increases in FEV1
and FVC during that period
(hereafter referred to as 4-year growth in FEV1
and FVC). All available pulmonary-function measurements
were used to estimate lung-function
growth curves, including measurements at ages
ranging from approximately 9 to 19 years in
cohorts C and D and 10 to 16 years in cohort E