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My stats memory is rusty, but... Doesn't a normal distribution typically arise during random sampling? I.e., if there's some statistic you calculate based on

My stats memory is rusty, but... Doesn't a normal distribution typically arise during random sampling? I.e., if there's some statistic you calculate based on a sample, then when you take a bunch of independent population samples, that statistic will tend to be normally distributed over those samples. If that's the only reason we'd typically expect to see a normal distribution, then I don't understand why we'd expect employee ratings to be normally distributed.

petre 4y ago
Exactly, they're not random samples, not normally distributed and the population is too low for a single team. It's all bs based on junk science. Lies, damned lies and "statistics".
bayesian_horse 4y ago
They may be normally distributed or may not be. Actually hard to tell even given the data. But you can make a plausible argument against the performance metric being normally distributed among your employees because that would mean the way you hired your employees was completely random with respect to that performance metric.
schnitzelstoat 4y ago
The way MSFT used to do it per team was way too small a sample even if it was randomly distributed. But of course it isn't randomly distributed because you hope you recruitment process isn't just picking up random people from the street. So yeah, it makes no sense - it's just cargo cult business school science.
soVeryTired 4y ago
Ignoring some techincalities, the normal distribuiton pops up when you add together a bunch of independent random values. So in 50 question exam, I might have a probability p of getting any question correct. My final score might be something like the sum of 50 biased coin tosses, which will be approximately normal. I don't think there's any reason to believe that employee scores (out of 100, say) should be normally distributed.
bart_spoon 4y ago
Yes, you are describing the sampling distribution, which is the distribution of a statistic like the mean. This is different from a distribution of an actual sample. The confusion people encounter comes from the fact that statistical nomenclature couldn’t have been more confusingly designed if one tried.

petre 4y ago

Exactly, they're not random samples, not normally distributed and the population is too low for a single team. It's all bs based on junk science. Lies, damned lies and "statistics".

bayesian_horse 4y ago

They may be normally distributed or may not be. Actually hard to tell even given the data. But you can make a plausible argument against the performance metric being normally distributed among your employees because that would mean the way you hired your employees was completely random with respect to that performance metric.

schnitzelstoat 4y ago

The way MSFT used to do it per team was way too small a sample even if it was randomly distributed. But of course it isn't randomly distributed because you hope you recruitment process isn't just picking up random people from the street. So yeah, it makes no sense - it's just cargo cult business school science.

soVeryTired 4y ago

Ignoring some techincalities, the normal distribuiton pops up when you add together a bunch of independent random values. So in 50 question exam, I might have a probability p of getting any question correct. My final score might be something like the sum of 50 biased coin tosses, which will be approximately normal. I don't think there's any reason to believe that employee scores (out of 100, say) should be normally distributed.

bart_spoon 4y ago

Yes, you are describing the sampling distribution, which is the distribution of a statistic like the mean. This is different from a distribution of an actual sample. The confusion people encounter comes from the fact that statistical nomenclature couldn’t have been more confusingly designed if one tried.