A sort-of-mathematician reads the newspapers

[Dave Birch] According to a middle eastern news service, the Saudi Arabian Monetary Agency (SAMA) announced that Saudis had withdrawn SR 68 billion worth of cash through the available ATM networks in the Kingdom through the first half of 2006. According to Al-Yaum newspaper, citing a SAMA report, Saudis had also executed 4,320,474,149 transactions through the available ATM’s networks in the Kingdom through the first half of 2006. The report added that the Saudi banks had issued 359,117,900 ATM cards through the first half of 2006. The total number of the ATM machines in the Kingdom amounted to 5,377 machines. Man, those must be some ATMs: one transaction at every machine every 17 seconds, 24×7.

Technorati Tags: ATM, banking, cash

Hold on, I thought, and did a quick google. I discovered that there was some scepticism at Bankwatch and I added to it. I knew that according to APACS the UK figures were nothing like that, and with a much higher population. So I checked (about 10 seconds) and found that the total of all withdrawals from ATMs was £172 billion last year, an average of £5,455 per second. There were 2.7 billion ATM withdrawals, an average of 86 withdrawals every second throughout the year. But there are 10 times as many ATMs in the UK (in fact, there were 58,286 cash machines at the end of last year).

But maybe people use cash more in Saudi Arabia, so the figures could still be correct. But wait, I thought, even in the US (according to the Feds August cash study), there were not even 6 billion ATM transactions in the entire USA for the whole of 2004 (this took me another 10 seconds to find out).

So, I thought (for another 10 seconds), maybe the Saudi figures are correct. That would be amazing. So (another 10 seconds) I googled and discovered that SAMA has a very helpful web site where you can even download their figures in Excel format. In case anyone is interested, here they are…

mon-22.xls

And, of course, the figures don’t look anything like the newspaper reports. In fact, they show just over 9 million ATM cards in issue and around 150 million withdrawals in the quarter (ie, about 600 million for the year, not the 17-odd billion implied by the newspaper). My guess is that the journalists have totaled the cumulative quarterly figures for the last N years to come up with a meaningless number that they incorrectly called “the total”. As they say, when you read about anything you know about in the newspaper, it’s always wrong.

While I was being distracted from doing anything useful by typing this entry, I was listening to a BBC news report concerning the record “A Level” passes this year, noting that most students are taking media studies instead of anything difficult like physics. Oh well. I took me less than a minute to find the truth, but I only looked for it because I’m used to looking at “money” statistics and have a rudimentary knowledge of arithmetic. But the crucial factor was the ability to estimate, hard won during a Physics degree. We’re a dying breed.

Incidentally, the title of this blog comes from a highly recommended read, “A Mathematician Reads the Newspaper” (John Allen Paulos).