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"If I put the purchases of hundreds or thousands of them in chronological order, then found 4 in a row that had failed, it wouldn't mean much (like the Aces exa
by greatreorx 18y ago
"If I put the purchases of hundreds or thousands of them in chronological order, then found 4 in a row that had failed, it wouldn't mean much (like the Aces example)."
But this is exactly what happened to your friend. You can't ignore the thousands of other Macbooks that were sold to calculate one number, but then try to apply that rate to those thousands.
"If I have a sample of only 4, and 3 failed, that means quite a bit more."
That means quite a bit more for that specific sample of 4 Macbooks - but no one cares about the failure rate for your 4 specific Macbooks. You proved that failure rate for those 4 Macbooks was exactly 75%. Nothing more, nothing less.
- byrneseyeview 18y agoYou proved that failure rate for those 4 Macbooks was exactly 75%. Nothing more, nothing less. Since you're being pedantic, I should point out that he's also proved that the total failure rate is at least three per however-many-Macbooks-there-are.
- mattmaroon 18y agoWell, you can argue about whether or not my sample was sufficiently random, but if it were, a failure of 3/4 indicates a VERY high probability that the overall sample has a higher failure rate than 10%. Again, that might be a failure rate for one production run. They were bought in different states, but all around the same time, so they may have all been made on the same day in the same place for all I know. And either way, it clearly doesn't speak to every product Apple makes. The whole point of the article wasn't to bash Apple, the Macbook Brick thread here just happened to be what started the thought. It was to point out that, mathematically speaking, a lot of times a small sample can tell you something with a very high degree of certainty.