Abstract
The purpose of this report was to analyse the effect on traffic accidents caused by the various measures taken in Finland to increase the use of vehicle running lights during daylight hours. It is shown that it is of great importance to arrange traffic accident statistics in such a way that it can be used for analysis of the effects of various types of measures. If the accident statistics available had contained more specific information about whether or not vehicles involved in multiple accidents had headlights on, a more direct analysis would have been possible.