I don't believe that ecofarm meant 5% of the population, instead it meant you could prove the hypothesis that "partial (especially minor) color blindness isn't abnormal" if you used 5% as your level of significance.
This
also shows an ignorance of what statistical significance is. Statistical significance would have
no bearing on normal or abnormal under
any circumstances.
Statistical significance ALWAYS, 100% of the time, refers to teh likluihood that the
results of a study occured by chance.
There's a reason I asked him what study he was referring to when he used that term.
He may not have used the words "5% of a population" but no matter
how you cut it, that's what his comment was doing.
Either way, you are not arguing the same thing. When something falls within two standard deviations (or 95%) it is considered normal. That is different than saying 95% of the population.
It isn't different at all. The 95% refers to the total population that falls within the range of 4 standard deviations of the distribution that "within 2 standard deviations" encompasses (two above the mean, two below the mean).
There would only be 2.2% of the population further than 2sd's above the mean, and there would only be 2.2% of the population more than 2sds below the mean.
If you use the two SD rule to define normal, then you are saying that 95% of the population is normal.
Tucker Case argued that using the two standard deviations as a model, then color blindness would be considered normal, which is inaccurate, unless the statistical analysis was done on the entire population.
Colorblindness doesn't fall on a bell curve, so I was actually using the 95% rule of thumb that coincides with the normal distribution. Once we make "normal" a product of percentages, where 95% are normal, and 5% are not, we have an easy way to calculate "normal" for distributions that don't follow the bell curve based on the percentage of population.
Colorblindness is believed to be as much as 10% of the male population. By using the rule of thumb related to percentages, it would be normal.