Watch out for outliers

[ffutures]

The blood transfusion service asked me to fill in an on-line survey today, with a chance of winning £100. So I did this, and all went swimmingly until I got to a question near the end; "how many times have you given blood?"

So I entered my guess, which was 106 times (can't actually remember except it's over 100) and it said I was wrong. So I tried again with 104, 105, and so forth, and again got this message. Eventually realised that they probably didn't actually have access to my records, so tried again with 99 - which worked. The twit who designed the survey had assumed that it only needed two figures... Fortunately there was a bit at the end to say what you thought of the survey, and I pointed out the mistake. Willing to bet I don't get any acknowledgement - or win the money!

Comments

[pauldormer.livejournal.com]

Back when I read Computer Weekly there was a Bug of the Week column.

Someone had a payroll program for a company in Dallas. They wanted to run it for the people in the Austin office but the print-outs were headed "Dallas". They didn't have the source code.

Someone went through a dump of the program and found the character string "Dallas" and changed it to "Austin".

The new program did print out with the correct heading. But it gave the wrong answers. Turned out that the programmer, to save space, had re-used the contents of the string as numerical constants in the calculations.

[ffutures.livejournal.com]

That's tight coding. Of course the big example of this is the original Elite, where every byte of the code was used to seed a non-random number generator. Which resulted in the programmers having to omit one of the game's galaxies because the generator design gave one system an obscene name, and it was easier to get rid of the galaxy than to change the way names were generated.