The ex-Cardiff University lecturer’s complicated formula is: O + (N x S) + Cpm/T + He.My, that does look complicated... what on earth could it all mean? Luckily there's an explanation for the formula in the article (although no explanation for why (N x S) is in brackets. You can read it below the fold.
Put simply, a value for being outdoors (O) was added to nature (N) multiplied by social interaction (S), added to childhood summer memories (Cpm) divided by temperature (T), and added to holiday excitement (He)Oh, right... that makes sense then. Or, erm... maybe it actually means absolutely nothing at all. Let's attempt to go through the equation bit by bit, and see how 'simple' it is.
Firstly, we'll try to figure out what we're doing with this formula. Are we maximising this quantity or are we minimising it? Outdoors is good, Nature is good, Social Interaction is good... we must be maximising.
Secondly, we'll try to work out the units. O is for outdoors. I've no idea what units we can measure 'Outdoors' in (or why anyone would choose to use an 'O' as a variable name) - perhaps we could measure it in time spent there? That kinda makes sense... maybe the units are time (of course, each of the terms in the sum must be the same units, as otherwise adding them together makes no sense).
Third, let's consider the next term in the sum: NS for Nature times Social Interaction. Wait... did that really say 'Nature x Social Interaction'? What on earth could that possibly mean? How does one multiply Nature by Social Interaction? In fact, how can one measure Nature? What units could you use? You might ask similar questions about Social Interaction... once you've managed to decide on units and measure them both, all you have to do is multiply them together. And remember that when we're done, this must all be measured in the same units as 'Outdoors' and 'Holiday excitement'.
Next we come to my favourite bit... Cpm/T. That's Cpm for 'childhood Summer memories' (no, I have no idea where that variable name comes from either) and T for temperature. Remember we decided we were probably maximising the quantity in the formula, since all the other things we've seen so far are the sorts of things that make people happy. Well, how do we maximise Cpm/T? That seems pretty simple... let T tend to zero!
Seriously. The formula suggests that colder days are happier - and apparently makes June 18 the Happiest Day of the Year. Arnall really doesn't put much effort into making this stuff up. He just decides on some quantities that he thinks might be relevant and writes down some suggestive variable names in an arbitrary order. He doesn't even bother to the formula internally consistent. How hard would it have been to write Cpm*T? Would that have looked less formula-y?
The final term is Holiday Excitement which, frankly, I can't be bothered to go into, apart from pointing out that He is a pointlessly confusing variable name for a 'scientific' formula.
Incidentally, in case this seems like you've heard it all before... you have. Last year the happiest day was June 19 (with exactly the same formula). In 2008 it was June 20 (I notice in that story that Arnall was already a 'former tutor at the University of Cardiff' two years ago. Presumably he hasn't managed to find himself a new post at a similarly respectable institution since, as that's still his qualification). In 2006 it was June 23, and in 2005 June 24 (I guess there was some actual news in 2007). Seriously, I hope they don't pay him to recycle this stuff every time... they could just copy last year's article.
Arnally pretty strongly suggests in the article that the formula always comes out to be the third Friday in June, which is slightly confusing, as I'm pretty sure it's impossible for the 23 to be the third Friday in any month, but maybe 2006 was special for some reason, or maybe he's just forgotten what he wrote 4 years ago. Also, I find it very hard to believe that either 'nature' or 'social interaction' is higher on a Friday than at the weekend, but then I'm not a 'former Cardiff University Tutor' (do I get to describe myself as 'Dr John Faben, former University of London Tutor if I do ever get round to finishing my thesis?)
I don't know why I bothered writing a post quite this long to dissect a formula that's quite so obviously inane publicity-seeking. Partly because it annoyed me, and partly because it's fun. But, just in case you missed it in all the excitement, remember this bit if you're ever tempted to take anything Cliff Arnall says seriously. In the formula, he divides by Temperature!
HT (as you might expect) to Ben Goldacre