NOxEmissions {robustbase} | R Documentation

## NOx Air Pollution Data

### Description

A typical medium sized environmental data set with hourly measurements of NOx pollution content in the ambient air.

### Usage

    data(NOxEmissions)

### 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.

### Source

René Locher (at ZHAW, Switzerland).

### See Also

another NOx dataset, `ambientNOxCH`.

### Examples

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

    ## Not run: ## 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))

    ## End(Not run)

[Package robustbase version 0.92-7 Index]