Incidence of Incidents

From time to time a new word is coined, or an old one revived, to pad out the vocabulary of jargon. If an old term is revived and welcomed back into the vocabulary, there are bound to be some people who neither know the term in its old usage, nor are quite certain what is meant to mean in its new. So there is scope for plenty of verbal mayhem.

We all know about incidents. They are 'happenings', whether road accidents, arguments, burglaries or misunderstandings; and the term 'incident' derives from Latin elements 'in', meaning in or on; and 'cado' meaning to fall. So an incident is something that 'befalls', a single occurrence - though of course you can have several similar incidents.

The word 'incidence' - a singular noun that unfortunately sounds exactly like the plural noun 'incidents' - derives from the same Latin elements, but in an abstract noun form, and normally means 'the act of falling', or 'frequency of occurrence'. You could perhaps regard a single human heart-beat as an 'incident', but the frequency of heart beat, explained as the number of beats per minute, could be said to be the 'incidence' of heart-beat. Similarly, a mugging in a certain street is an 'incident'; the frequency of muggings in that street in a given period is the 'incidence' of muggings.

But because incidents and incidence sound exactly the same, some of those who are not familar with the meaning of the latter term assume that incidence is just a posh term for incident, and proceed to speak or write (wrongly) of 'an unusual number of incidencies'.

Incidents may be a matter for the police to consider*; but incidence is the concern of the statitician or mathematician.

* But of course, most incidents, or happenings, are not bad ones: it's just that the term is a favourite among
those who have to observe or record the less pleasant aspects of human behaviour.

A 'co-incidence' describes (strictly speaking) when two 'incidents' happen at the same time: old friends Mr X and Mr Y both chance to turn up at the same bus stop at the same moment.

Incidence of Incidents