Tasks of DEBtox

DEBtox basically serves six tasks:

1. Estimation of parameters, their asymptotic standard deviations and their correlation coefficients. The different modes of action of the compound are described by different models: one for the survival experiment, three for body growth, five for reproduction and three for population growth.
2. Measurement of the goodness of fit of the selected model and a graphical presentation of data together with the model expectations for the time and the concentration profiles.
3. Calculation of the profile ln likelihood function for the no-effect concentration. The results are presented graphically. DEBtox reads this graph and can produce confidence intervals, if the user has selected the confidence level.
4. Calculation of EC(e,t) values, ET(e,c) values and ER(c,t) values and their standard deviations, if the user has selected the concentration c, the exposure time t and/or the effect level e. DEBtox can present the effect as a function of concentration and exposure time graphically, using isoclines.
5. Statistical tests on any parameter value or combination of parameter values. This is done on the basis of the likelihood ratio test.
6. Analysis of the residuals. The residuals, i.e. the differences between observed values and model expectations, can be plotted as functions of the concentration, the exposure time or the response.

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