&gt; The parent made no error in his language.<p>The parent claimed a 3-4 point in an individual&#x27;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.<p>The standard deviation of a non-identical population has no relation to the statistical significance of a change for an individual.<p>Let&#x27;s say the standard deviation of heights for males is 2.8 inches; that is what some of the internet claims. Let&#x27;s use two standard deviations as statistically significant. That means, if someone woke up one day and was 6&#x27;3&quot; instead of 5&#x27;10&quot;, that was not a &quot;significant change&quot; because they only changed in height by 5 inches.<p>Standard deviation for a non-identical population is completely unrelated to the significance of changes for an individual.