I refer to the extensive report on road safety carried in your newspaper 8 April.

It is unfortunate that the report completely ignores important national and international data. Malta has one of the lowest national speed limits in the world (excluding Vietnam). It has one of the best road safety statistics in Europe, but the worst roads (bar Romania).

I have repeatedly corrected the misconception that road death rates in Malta are increasing. The rates of road vehicle accidents causing grievous injury and death, taken together, have remained stable over the past years (308 in 2012, 283 in 2013, 302 in 2014, 317 in 2015 and 316 in 2016). If one looks at the official figures for road deaths in the years from 2012 to 2017 (11 in 2012, 18 in 2013, 11 each in 2014 and 2015, 23 in 2016 and 19 in 2017), a positive trend does not emerge. However, one might be tempted to interpret variations due to the small number effect and treat them as real effects. This is wrong.

To put any alternative argument to rest, I have calculated the standard deviation of both trends. The standard deviation is a mathematical measure of the natural variation due to chance. The standard deviation of road death fatality figures between 2012 and 2016 is approximately 5.5, while that of injuries is 15.3. As such, in the 2012 to 2016 period of observation, any road death rate in the range between four and 26, and any total road injury and fatality figure between 260 and 320 (rounded off), is within the range of variation to be expected, due simply to chance (i.e. within 1.96 standard deviations of the mean). The assumption of normality of the distribution does not strictly hold, but, if anything, a non-parametric test would give a wider confidence interval.

A most recent trend in local road death rates has been linked to an abnormal number of motorcycle, not car, accidents. While motorcycles only represent 6.6 per cent of all vehicles on the road, they were involved in 20 per cent of the accidents resulting in injuries in 2016.

Speed is often demonised, when it is a fact that roads which safely allow cars to travel at higher speeds are among the safest per kilometre travelled.

Jean Karl Soler

Rabat