Comments for Joyfeed

Comment on The Mathematics of Number Plate Spotting by Christian Perfect

Christian Perfect — Sun, 11 Sep 2011 09:24:00 +0000

The maths looks pretty spot on, so I wrote a python script to model the problem: http://checkmyworking.com/misc/nps.py

The output I got was:
Mean of 100 goes of CNPS upto 1000: 999246.22 cars
Mean of 100 goes of NCNPS upto 1000: 7407.75 cars

Which agree with your numbers pretty closely!

Comment on The Mathematics of Number Plate Spotting by joyfeed

joyfeed — Tue, 06 Sep 2011 16:54:42 +0000

It seems that I have oversimplified the harmonic series formula, most notably omitting the Euler constant, so I am working on that now. Regarding the points raised above, however:

hoppo: the assumption is that each number plate is independent of the next so could contain the same number again or any number from 1 – 999, and that every number plate viewed has an equal chance of containing the number we are looking for, i.e. a 1/999 chance, and so the average number of plates we would have to see before we spotted the specific number we were looking for would be 999. Your point about the skilled Herring-style operator is quite right though, and in practice non-random elements such as memory, notebooks and tip-offs from friends would all come into play to reduce the total we would need to view before a successful spot.

Ryan: agreed, see point above.

Warren: Absolutely – I spotted 202 only this week after I think about a year of looking. The chances of any of us completing this idiotic and pointless task are descending exponentially down the probability toilet.

Comment on The Mathematics of Number Plate Spotting by Warren

Warren — Tue, 06 Sep 2011 13:52:59 +0000

You should also try to factor in that cnps and ncnps is becoming harder in a non-linear fashion due to the removal of older cars from the pool of vehicles.

I’ve been stuck on 250 for a year now.

Comment on The Mathematics of Number Plate Spotting by hoppo

hoppo — Tue, 06 Sep 2011 11:48:26 +0000

“Assuming that there is an even distribution of numbers then on average it will take 999 distinct number plates before the given number is spotted.”

Not true. This assumes that you will only spot a given number after you’ve seen every other number in random order first. You would have to be pretty unlucky for this to happen?

In reality, if we assume that every number has equal frequency then it’s equally likely that it will be the next number you see, or the 999th, or any number in between.

So on average, you will have to look at about 500 different numbers to spot the next one you need.

Of course, skilled players such as Mr Herring keep detailed notes of where upcoming numbers might be lurking (by ‘prespotting’ neighbour’ cars, etc.) so in actual fact the true average number of numberplates you would need to look at to advance your score would probably be considerably less than 500.

Comment on The Mathematics of Number Plate Spotting by Ryan Cullen

Ryan Cullen — Tue, 06 Sep 2011 11:45:08 +0000

You are also assuming that you have no knowledge of the next plate, however a good CNPSer would have notes reminding them where upcoming plates are regularly located (or even a website which had a twitter account to send DMs after plates were found, and yes I know how sad that was).

Comment on The Mathematics of Number Plate Spotting by Joshua

Joshua — Tue, 06 Sep 2011 11:06:24 +0000

Of course, with NCNPS comes the less measurable difficulty of remembering which numbers you have and haven’t spotted. Under CNPS, you only need to remember the last number spotted.

Comment on Monster Munch by simon

simon — Mon, 06 Oct 2008 13:20:49 +0000

if this credit crunch gets any bigger, it too will be a monster munch

Comment on All Creatures Great and Small by Dogman

Dogman — Fri, 03 Oct 2008 09:57:56 +0000

This piece is very good. It brought to the surface of my recollection a conversation I heard in Northampton Job Centre (or whatever epithet they ‘employed’ to mean ‘Job Centre’ in 1996).

I was sat on one of the grimy chairs in the ‘waiting’ area, beside a man. He was waiting too. Presently, a woman came across and sat down next to the man. They evidently knew one another, and grunted recognition. The exact conversation (and I remember it syllable-for-syllable) was:

SHE: ‘right?
HE: ‘right.
[pause]
SHE: How’s dog?
HE: ‘right.
[pause]
SHE: How’s cat?
HE: ‘right. [pause] Hates dog.

The conversation I think is one of the all-time greats.

Comment on A Restoration by leila

leila — Sun, 09 Dec 2007 21:04:34 +0000

I was trying to explain this essay to a group of assembled ATR contributers last night and one of them said, “Hang on – is this something people do? Tip a tub upside down onto a plate and then…” It took me a long time to reassure them you’d dropped it accidentally, and it wasn’t the normal way of serving margarine. Maybe it should be though.

Comment on A Restoration by Joe French

Joe French — Mon, 03 Dec 2007 21:02:33 +0000

Sounds like you need to invest in some lard. Stays as a mass and is delicious on toast.