R Dataset / Package MASS / Traffic


On this R-data statistics page, you will find information about the Traffic data set which pertains to Effect of Swedish Speed Limits on Accidents. The Traffic data set is found in the MASS R package. You can load the Traffic data set in R by issuing the following command at the console data("Traffic"). This will load the data into a variable called Traffic. If R says the Traffic data set is not found, you can try installing the package by issuing this command install.packages("MASS") and then attempt to reload the data. If you need to download R, you can go to the R project website. You can download a CSV (comma separated values) version of the Traffic R data set. The size of this file is about 3,009 bytes.

Effect of Swedish Speed Limits on Accidents


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.




This data frame contains the following columns:


1961 or 1962.


of year.


was there a speed limit?


traffic accident count for that day.


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


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


Dataset imported from https://www.r-project.org.

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Attachment Size
dataset-72987.csv 2.94 KB
Dataset License
GNU General Public License v2.0
Documentation License
GNU General Public License v2.0

This documentation is licensed under GPLv3 or later.