NOxEmissions: NOx Air Pollution Data

Description

A typical medium sized environmental data set with hourly measurements of $N O x$ pollution content in the ambient air.

Usage

data(NOxEmissions, package="robustbase")

Arguments

Format

A data frame with 8088 observations on the following 4 variables.

julday: day number, a factor with levels 373 ... 730, typically with 24 hourly measurements.
LNOx: $\log$ of hourly mean of NOx concentration in ambient air [ppb] next to a highly frequented motorway.
LNOxEm: $\log$ of hourly sum of NOx emission of cars on this motorway in arbitrary units.
sqrtWS: Square root of wind speed [m/s].

Details

The original data set had more observations, but with missing values. Here, all cases with missing values were omitted (na.omit(.)), and then only those were retained that belonged to days with at least 20 (fully) observed hourly measurements.

Examples

Run this code

data(NOxEmissions)
plot(LNOx ~ LNOxEm, data = NOxEmissions, cex = 0.25, col = "gray30")

if (FALSE) ## these take too much time --
 ## p = 340  ==> already Least Squares is not fast
 (lmNOx <- lm(LNOx ~ . ,data = NOxEmissions))
 plot(lmNOx) #->  indication of 1 outlier

 M.NOx <- MASS::rlm(LNOx ~ . , data = NOxEmissions)
 ## M-estimation works
 ## whereas  MM-estimation fails:
 try(MM.NOx <- MASS::rlm(LNOx ~ . , data = NOxEmissions, method = "MM"))
 ## namely because S-estimation fails:
 try(lts.NOx <- ltsReg(LNOx ~ . , data = NOxEmissions))
 try(lmR.NOx <- lmrob (LNOx ~ . , data = NOxEmissions))

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