Accuracy As with any
statistical data, the
accuracy of the findings may be challenged. In this case, for the following reasons: • Some studies may allow subjects to
self-report values. Generally speaking, self-reported height tends to be taller than measured height, although the overestimation of height depends on the reporting subject's height, age, gender and region. • Test subjects may have been invited instead of
random sampling, resulting in
sampling bias. • Some countries may have significant height gaps between different regions. For instance, one survey shows there is difference in mean height between the tallest state and the shortest state in Germany. Under such circumstances, the mean height may not represent the total population unless sample subjects are appropriately taken from all regions with using
weighted average of the different regional groups. • Different
social groups can show different mean height. According to a study in France, executives and professionals are taller, and university students are taller than the national average. As this case shows, data taken from a particular social group may not represent a total population in some countries. • Height measurement can vary over the course of a day, due to factors such as a decrease from exercise done directly before measurement (i.e. inversely correlated), or an increase after lying down for a significant period of time (i.e. positively correlated). For example, one study revealed a mean decrease of in the heights of 100 children from getting out of bed in the morning to between 4 and 5 p.m. that same day. Such factors may not have been controlled in all of the following studies. • It should be remembered that the stature of a man standing, in adult males, varies between the normal individual extremes of – and that can lead to mean results lower than (very short height) or ≥180–182 cm (about 6 ft) (very tall height): but these extreme results are based on series "in which a choice has occurred, voluntarily or not". • According to the geographical-anthropological study by Asutosh Goswami
et al. (2023), 95% of the global adult population has average statures between and .
Measured and self-reported figures Note: where available,
standard deviation (SD) is listed under sample population / age range ==Notes==