Traffic                 package:MASS                 R Documentation

Effect of Swedish Speed Limits on Accidents

Description:

     An experiment was performed in Sweden in 1961-2 to assess the
     effect of a speed limit on the motorway accident rate.  The
     experiment was conducted on 92 days in each year, matched so that
     day 'j' in 1962 was comparable to day 'j' in 1961.  On some days
     the speed limit was in effect and enforced, while on other days
     there was no speed limit and cars tended to be driven faster. The
     speed limit days tended to be in contiguous blocks.

Usage:

     data(Traffic)

Format:

     This data frame contains the following columns:

     'year' 1961 or 1962

     'day' of year

     'limit' was there a speed limit?

     'y' traffic accident count for that day

Source:

     Svensson, A. (1981) On the goodness-of-fit test for the
     multiplicative Poisson model. _Annals of Statistics,_ *9*,
     697-704.

References:

     Venables, W. N. and Ripley, B. D. (1999) _Modern Applied
     Statistics with S-PLUS._ Third Edition. Springer.

