NIST/ITL StRD | |
Dataset Name: Rat43 (Rat43.dat) | |
File Format: ASCII | |
Starting Values (lines 41 to 44) | |
Certified Values (lines 41 to 49) | |
Data (lines 61 to 75) | |
Procedure: Nonlinear Least Squares Regression | |
Description: This model and data are an example of fitting | |
sigmoidal growth curves taken from Ratkowsky (1983). | |
The response variable is the dry weight of onion bulbs | |
and tops, and the predictor variable is growing time. | |
Reference: Ratkowsky, D.A. (1983). | |
Nonlinear Regression Modeling. | |
New York, NY: Marcel Dekker, pp. 62 and 88. | |
Data: 1 Response (y = onion bulb dry weight) | |
1 Predictor (x = growing time) | |
15 Observations | |
Higher Level of Difficulty | |
Observed Data | |
Model: Exponential Class | |
4 Parameters (b1 to b4) | |
y = b1 / ((1+exp[b2-b3*x])**(1/b4)) + e | |
Starting Values Certified Values | |
Start 1 Start 2 Parameter Standard Deviation | |
b1 = 100 700 6.9964151270E+02 1.6302297817E+01 | |
b2 = 10 5 5.2771253025E+00 2.0828735829E+00 | |
b3 = 1 0.75 7.5962938329E-01 1.9566123451E-01 | |
b4 = 1 1.3 1.2792483859E+00 6.8761936385E-01 | |
Residual Sum of Squares: 8.7864049080E+03 | |
Residual Standard Deviation: 2.8262414662E+01 | |
Degrees of Freedom: 9 | |
Number of Observations: 15 | |
Data: y x | |
16.08E0 1.0E0 | |
33.83E0 2.0E0 | |
65.80E0 3.0E0 | |
97.20E0 4.0E0 | |
191.55E0 5.0E0 | |
326.20E0 6.0E0 | |
386.87E0 7.0E0 | |
520.53E0 8.0E0 | |
590.03E0 9.0E0 | |
651.92E0 10.0E0 | |
724.93E0 11.0E0 | |
699.56E0 12.0E0 | |
689.96E0 13.0E0 | |
637.56E0 14.0E0 | |
717.41E0 15.0E0 |