NO2: Log-linear (multiplicative) model 1 evaluating the quadruplets of continuous NO2-measurements.

Regression coefficient, robust standard errors of coefficient, t-statistic, two-sided P-value, and 95%-confidence interval of coefficient. The relative LEZ effect estimate is given by the coefficient E (relative effect E = 0.979, 95% Conf. Interval = 0.979, 0.980.Covariables, before taking logs: difference in reference stations Ref.diff in µg/m3, centered reference baseline concentration Ref.base in µg/m3, centered index baseline concentration Ind.base in µg/m3, 1/H = 1/(height of inversion layer) in 1/m, 1/V = 1/(wind velocity+0.01) in (m/s)−1, 1/P = 1/(amount of precipitation+0.01) (mm/h)−1, centered difference in time Time.diff in years.