Reference tables and sources

Every number in this app comes from the two datasets below, with nothing copied by hand. The original files were downloaded as they are and converted, and a test locks the conversion to the originals.

Sources and terms of use

Data not used

KDCA Korean children and adolescents growth chart (2017) (15076588). Licensed as Korean public work type 2 (attribution, no commercial use), so an ad-supported app does not use it. https://www.data.go.kr/data/15076588/fileData.do

How the numbers are computed

Each month's row has three values, L, M and S. M is the middle value for that month, S the spread, and L the power that straightens the skew.

For a measured value x, z is ((x/M)^L - 1) / (L x S) when L is not 0, and ln(x/M) / S when L is 0.

The percentile is the cumulative value of the bell curve times 100, rounded down to a whole number. The NHIS percentile-to-z table follows exactly that rule, and a test checks all 198 boundaries of that table.

Age is the whole number of completed months, compared with that month's row. There is no interpolation between months and no tail correction beyond z of 3. The table was published without one and we follow the table.

Range covered

Percentile tables by month

For each month, the weight, height, head circumference and body mass index values at percentiles 3, 5, 10, 25, 50, 75, 90, 95 and 97 for boys and girls.

Boy

Girl