FFEPT

The analysis of the results below uses only the data couples (weight + length). The weight-only are not used.

The point cloud below allows us tu process the theoric chart of te weight/size ratio for the species of the studbook.

Process of the theoric chart

Data are adjusted with a 3rd degree polynom, i.e. it is such as y = a + bx + cx² + dx³

We use the mathematic formulas of the least squares to get 4 equations with 4 unklnowns a, b, c et d :

Thus :
534 = 6 a + 30.05 b + 230.1025 c + 2264.130125 d
5959.95 = 30.05 a + 230.1025 b + 2264.130125 c + 25100.94540625 d
70413.3075 = 230.1025 a + 2264.130125 b + 25100.94540625 c + 294046.22887531 d
850645.044375 = 2264.130125 a + 25100.94540625 b + 294046.22887531 c + 3534612.9514425 d

With the Gauss pivot we get :
534 = 6 a + 30.05 b + 230.1025 c + 2264.130125 d
3285.5 = 0 a + 79.602083333333 b + 1111.7001041667 c + -10227.818271875 d
49934.185 = 0 a + 1111.7001041667 b + 16276.418655208 c + 207215.89519401 d
649137.46325 = 0 a + 13761.427030208 b + 207215.89519401 c + 2680232.0809538 d
then :
534 = 6 a + 30.05 b + 230.1025 c + 2264.130125 d
3285.5 = 0 a + 79.602083333333 b + 1111.7001041667 c + -10227.818271875 d
4049.8244494752 = 0 a + 0 b + 750.73050922164 c + 350054.70244769 d
81147.699484401 = 0 a + 0 b + 15027.710886046 c + 4448394.0301486 d
then :
534 = 6 a + 30.05 b + 230.1025 c + 2264.130125 d
3285.5 = 0 a + 79.602083333333 b + 1111.7001041667 c + -10227.818271875 d
4049.8244494752 = 0 a + 0 b + 750.73050922164 c + 350054.70244769 d
80.53860791745 = 0 a + 0 b + 0 c + -2558808.6851625 d

Thus :

d = -3.1475040859623E-05
b = -34.273182698826
c = 5.4091879651304
a = 53.218788323586

We get the chart below (in red) :
y = 53.22 + -34.27 x + 5.41 x² + -0.00 x³

simplified by (in green) :
y = -34.27 x + 5.41 x²




Bodymass index (BMI) of all the Sternotherus odoratus

BMI = Weight (g) / size² (cm.mm)



Histogram of the distribution of the BMI of all the Sternotherus odoratus



Histogram of the distribution of the BMI of all the Sternotherus odoratus juveniles



Histogram of the distribution of the BMI of all the Sternotherus odoratus adults



The Bodymass index (BMI) is "the weight divided by the square of the size". Do it for yourself with your size in m,cm and your weight in kg, You will get a value between 20 and 25. A value above is said an overweight (and the same goes below 20). It is a good index, ask your doctor.