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The bell curve is not a curve of programming ability of ALL people - for any given skill that would obviously be massively skewed to zero skill, since most peop

The bell curve is not a curve of programming ability of ALL people - for any given skill that would obviously be massively skewed to zero skill, since most people wouldn't be participating. The curve is for people who HAVE programmed. It is irrelevant what the barrier is - the curve is only describing people who have crossed that barrier and written some code. You wouldn't include dogs in a bell curve of human height - the thing being measured first has to be a member of the group that is being described.

thomasahle 11y ago
What about this model: Say programming skill is more or less proportional to the time spent programming. Further say that at any moment a person has a certain probability of leaving the industry. In that case the skill curve over the population should be a geometric, hockeystick like curve. It wouldn't make sense that the majority of people had experience in the 5-8 years interval say.
peterfirefly 11y ago
It is still not likely to be bell shaped. Of course there is a /distribution/ and of course it is not shaped like a vertical line -- but it is very unlikely to be a normal distribution.
- CPLX 11y ago
  Why? In general one would assume that a distribution of this type would be normal absent evidence to the contrary right? What is that evidence to the contrary?
  - learnstats2 11y ago
    If we take robinrob's point, and measure only "people who have programmed", then I would still expect a very positively skewed distribution. There are really a lot of people in the "I tried it and didn't like it" category. For almost any boundary you choose, a majority of people will sneak in just over that boundary, leaving a long one-sided tail. This skewed distribution would appear even if you cut a Normal distribution. A Normal distribution occurs when everyone is expected to be at the same average level but could move up and down equally due to many random factors. When learning skills, people generally start at a 0 level and generally move up. That won't be Normal. If you take a cohort of programmers with exactly the same experiences, that could plausibly follow a Normal distribution of skill. If you take e.g. all professional programmers, that won't.
    - CPLX 11y ago
      > A Normal distribution occurs when everyone is expected to be at the same average level but could move up and down equally due to many random factors. When learning skills, people generally start at a 0 level and generally move up. That won't be Normal. Aha, yes that's an excellent point.
  - peterfirefly 11y ago
    If you chop off the left side of a bell curve, is the remaining part suddenly bell shaped?

thomasahle 11y ago

What about this model: Say programming skill is more or less proportional to the time spent programming. Further say that at any moment a person has a certain probability of leaving the industry. In that case the skill curve over the population should be a geometric, hockeystick like curve. It wouldn't make sense that the majority of people had experience in the 5-8 years interval say.

peterfirefly 11y ago

It is still not likely to be bell shaped. Of course there is a /distribution/ and of course it is not shaped like a vertical line -- but it is very unlikely to be a normal distribution.

CPLX 11y ago
Why? In general one would assume that a distribution of this type would be normal absent evidence to the contrary right? What is that evidence to the contrary?
- learnstats2 11y ago
  If we take robinrob's point, and measure only "people who have programmed", then I would still expect a very positively skewed distribution. There are really a lot of people in the "I tried it and didn't like it" category. For almost any boundary you choose, a majority of people will sneak in just over that boundary, leaving a long one-sided tail. This skewed distribution would appear even if you cut a Normal distribution. A Normal distribution occurs when everyone is expected to be at the same average level but could move up and down equally due to many random factors. When learning skills, people generally start at a 0 level and generally move up. That won't be Normal. If you take a cohort of programmers with exactly the same experiences, that could plausibly follow a Normal distribution of skill. If you take e.g. all professional programmers, that won't.
  - CPLX 11y ago
    > A Normal distribution occurs when everyone is expected to be at the same average level but could move up and down equally due to many random factors. When learning skills, people generally start at a 0 level and generally move up. That won't be Normal. Aha, yes that's an excellent point.
- peterfirefly 11y ago
  If you chop off the left side of a bell curve, is the remaining part suddenly bell shaped?