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This guide outlines data handling, fitting, software packages, and statistical analyses for reporting kinetic degradation results with examples and guidelines for comprehensive reporting.
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FOCUS Degradation Kinetics, Ton van der Linden, January 27, 2005 Guidelines for reporting
Outline • Data • Fitting • software package • model and settings • parameters and restrictions • statistics • Results • tables • graphs • statistics
Data • Data handling • outliers (reasons, statistical analyses, ..) • LOQ / LOD • weighting • All original values
Data example Outlier, Grubb’s test, = 0.05 In analysis as 0.5 * LOD Disregarded in kinetic analysis
Software package identification Examples • Berkeley Madonna 8.0.1 (2003) • ModelMaker 4 (2004) • MATLAB 6.51(2003) • Including toolbox Mfit 4.2 (1999)
Package settings Report all user adjustable settings: • Integration method • Optimisation object function • Iteration tolerance
Kinetic model • Implementation in software package • Concept • Schematic (if applicable)
Kinetic model, example Hockey-stick implementation in B.Madonna 8 METHOD RK4 STARTTIME = 0 STOPTIME=100 DT = 0.001 d/dt (Y) = if time < tb then - k1 * Y else -k2 * Y Init Y = 100. k1 = 0.01 k2 = 0.1 tb = 10
Parameters, etc Report: • fixed values • initial values of fitted • substances • parameters • restrictions on parameters At least two different sets of initial values should be used in order to check for global minimum in optimisation routine
Statistics • name of test • principle • confidence level • reference • Statistical software package • name • version • reference
Results • Table with DT / DegT values • uncertainty • extrapolation beyond experimental data • Visual • plot of predicted and fitted values vs time • plot of residuals • Statistical • 2 of the fit • uncertainty measures of parameters
Conclusions A report of kinetic analyses contains: • all information necessary to allow independent duplication of the results and verification with an alternative package • all diagrams and statistical measures underpinning intermediate and final results