Started by Brocke, Aug 31, 2012, 04:29:49 PM
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QuoteBirthday paradoxExperts use an analogy called the birthday paradox to explain that the way you search for a DNA profile can dramatically affect your chances of finding a match. In some circumstances, matches are far more likely than many people think.Imagine you're at a party with 99 other guests. If you randomly pull aside one of them, the odds he or she will share your day and month of birth are 1 in 365.But the probability that anyone at the party shares your birthday is far higher: about 1 in 4. When you compare your birthday with 99 other people's, each comparison makes a match more likely. (The math: Multiply the odds of 1/365 by 99, the number of comparisons, to get the approximate probability.)For the same reason, the odds that anyone at the party shares a birthday with anyone else are higher still. In fact, it's almost a certainty. As everyone looked for a match with everyone else, they made 4,950 comparisons. (The math: Multiply 100 people by the 99 other guests they compare themselves with, then divide by two because people who compare with each other count as a single comparison.)How many people need to be at the party for it to be likely that two guests share a birthday?The answer may surprise you: just 23.
QuoteAccording to a 2008 article in the New Yorker, close buttons don't close the elevator doors in many elevators built in the United States since the 1990s. In some elevators the button is there for workers and emergency personnel to use, and it only works with a key. The key-only settings isn't always active though, as the blog Design with Intent asserts. Each elevator is different. In some, the emergency function requires a long-press of several seconds longer than the average user attempts.
QuoteNon-functioning mechanisms like this that motivate you to fool yourself are called placebo buttons, and they're everywhere.Computers and timers now control the lights at many intersections, but at one time little buttons at crosswalks allowed people to trigger the signal change. Those buttons are mostly all disabled now, but the task of replacing or removing all of them was so great most cities just left them up. You still press them though, because the light eventually changes.In an investigation by ABC news in 2010, only one functioning crosswalk button could be found in Austin, Texas; Gainsville, Fla.; and Syracuse, NY.