This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...The method of showing distribution just described is not the only method used for this purpose. Francis Galton t determines the actual distribution of the observations in a series at intervals of 5 or 10 per cent. from the median or 50 " percentile grade." The calculation of the median value (mean) or 50 percentile ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...The method of showing distribution just described is not the only method used for this purpose. Francis Galton t determines the actual distribution of the observations in a series at intervals of 5 or 10 per cent. from the median or 50 " percentile grade." The calculation of the median value (mean) or 50 percentile grade has already been described: that for the 5, 10, 20 and other percentile grades is similar in The plates are placed after the index at the end of the number, t Natural Inheritance. London, 1889. principle. The percentile grades of the heights of girls, aged 9, are as follows: --TABLE No. 8. The Percentile Distribution Op The Heights Of Girls, Aged 9. The Probable Error of the Average can be determined by means of the formula where E = the probable error of the average, d = the probable deviation of an individual from the average, n = the number of observations in the series. Substituting the values determined for the heights of girls, aged 9, we have--E= = 0.079 cm. V 2122 The values of E are given in Table No. 9. Formulas (1), (2), (3) and (5) and Table No. 6 are taken from L. Stieda's admirable article: Ueber die Anwendung der Wahrscheinlichkeitsrechnung in der anthropologischen Statistik. Archiv. fur Anthropologie, Bd. xiv., 1882, p. 167-182. The mean or average of the observations at any age in the period of growth is typical of the child at that age, and a comparison of the means at different ages will reveal the law of growth of the type. Again, the mean of the observations at any deviation from the mean of the whole number, for example the height at a deviation of + d from the mean, or, if Galton's method is employed, the height at any percentile grade, is the type of those who stand at a certain degree of deviatio...
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