[cant_kant]

"Considering the standard deviation for IQ is 15 points"

The standard deviation for the distribution of IQ is 15 points.

The standard deviation of the errors of measurement associated with measuring IQ is 3 points.( ie: the standard error of measurement aka SEM)

I would be willing to have 3 fingers of my left hand ( not including my thumb ) amputated to improve my IQ by 1 standard deviation.

For more on Standard Error of Measurement, see http://www.csus.edu/indiv/b/brocks/Courses/EDS%20245/Handout...

[corndoge]

What is your point? The parent made no error in his language. The inferred meaning of 'standard deviation' in this context is 'standard deviation for distribution'. The parent referred to an improvement of 3-4 IQ points, not standard deviations.

[cowsandmilk]

> The parent made no error in his language.

The parent claimed a 3-4 point in an individual's IQ is statistically meaningless by point to the standard deviation of IQs for an entire population. That is either (a) misguided or (b) intentionally misleading.

The standard deviation of a non-identical population has no relation to the statistical significance of a change for an individual.

Let's say the standard deviation of heights for males is 2.8 inches; that is what some of the internet claims. Let's use two standard deviations as statistically significant. That means, if someone woke up one day and was 6'3" instead of 5'10", that was not a "significant change" because they only changed in height by 5 inches.

Standard deviation for a non-identical population is completely unrelated to the significance of changes for an individual.

[foota]

I believe the point is that standard dev for distribution is complete meaningless when talking about measuring a person's iq and increase thereof.

[cbd1984]

Out of respect for people who don't like being surprised, that link is a PDF.

[cbd1984]

That link is a PDF.