When dealing with statistics there are two seemingly innocuous phrases that should set your alarm bells ringing.  They are slipped into so many predictions almost as a matter of course, and we all too often ignore them.

They are:

“Other things being equal” sometimes given in Latin “ceteris paribus” as if that made it more helpful!


“If present trends continue”.

Just ask yourself, or even ask whoever is making the statement, what reasons are there to suppose that all relevant “other things” are or will remain equal, or whether present trends will continue, and for how long?

I have seen ridiculous scare stories about increases in accidents, crimes, diseases and all kinds of social ills, where the writers wanted us to believe the recorded rates of increase would go on for ever, or at least until we had all been killed!

Similarly, I have seen sales projections which seem to assume we are all going to continue buying cars, clothes, shoes, fridges and other products until we have got nowhere to put them.

The sensible question would be, “at what point will the rate of increase start to slow and at what point will it start to decrease?”  Think of a graph rising, flattening and then falling.

In the same way, ask what “other things” need to remain constant and how likely is it that they will.  Do the prophets of doom, or of utopia, not know that we live in an ever-changing world?

One swallow does not make a summer!