m) man and 8 ft 0 in (2.44 m) woman, and seven other independent skeletons measuring between 8 ft 0 in (2.44 m) and 10 ft 0 in (3.05 m). an image and stone tablet were found with the giants. adult height between populations often differs significantly. for example, the average height of women from the czech republic is greater than that of men from malawi. this may be caused by genetic differences, childhood lifestyle differences (nutrition, sleep patterns, physical labor), or both. depending on sex, genetic and environmental factors, shrinkage of stature may begin in middle age in some individuals but tends to be universal in the extremely aged. this decrease in height is due to such factors as decreased height of inter-vertebral discs because of desiccation, atrophy of soft tissues, and postural changes secondary to degenerative disease. working on data of indonesia, the study by baten, stegl and van der eng suggests a positive relationship of economic development and average height. in indonesia, human height has decreased coincidentally with natural or political shocks. average height around the world main article: average human height by country a textile label showing the difference in average height around the world as shown on this polo shirt. what is a medium size in the united states and europe becomes large size for asia as with any statistical data, the accuracy of such data may be questionable for various reasons: some studies may allow subjects to self-report values. generally speaking, self-reported height tends to be taller than its 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 chosen randomly, resulting in sampling bias. some countries may have significant height gaps between different regions. for instance, one survey shows there is 10.8 centimetres (4.3 in) gap 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 2.6 centimetres (1.0 in) taller, and university students are 2.55 centimetres (1.0 in) 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. a relatively small sample of the population may have been measured, which makes it uncertain whether this sample accurately represents the entire population. the height of persons can vary over a day, due to factors such as a height increase from exercise done directly before measurement (normally inversely correlated), or a height increase since lying down for a significant period (normally inversely correlated). for example, one study revealed a mean decrease of 1.54 centimetres (0.6 in) 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 some of the studies. men from bosnia and herzegovina, the netherlands, croatia, serbia and montenegro have the tallest average height. dinka people are sometimes noted for their height. with the tutsi of rwanda, they are believed to be the tallest people in africa. roberts and bainbridge reported the average height of 182.6 cm (5 ft 11.9 in) in a sample of 52 dinka agaar and 181.3 cm (5 ft 11.4 in) in 227 dinka ruweng measured in 1953–1954. other studies of comparative historical height data and nutrition place the dinka as the tallest people in the world. measurement crown-rump length is the measurement of the length of human embryos and fetuses from the top of the head (crown) to the bottom of the buttocks (rump). it is typically determined from ultrasound imagery and can be used to estimate gestational age. until two years old, recumbent length is used to measure infants. length measures the same dimension as height, but height is measured standing up while the length is measured lying down. in developed nations, the average total body length of a newborn is about 50 cm (20 in), although premature newborns may be much smaller. standing height is used to measure children over two years old and adults who can stand without assistance. measure is done with a stadiometer. in general, standing height is about 0.7 cm (0.28 in) less than recumbent length. surrogate height measurements are used when standing height and recumbent length are impractical. for sample chumlea equation use knee height as indicator of stature. other techniques include: arm span, sitting height, ulna length, etc.