The function fits the SFO, IORE and DFOP models using mmkin and returns an object of class nafta that has methods for printing and plotting.

nafta(ds, title = NA, quiet = FALSE)

Arguments

ds

A dataframe that must contain one variable called "time" with the time values specified by the time argument, one column called "name" with the grouping of the observed values, and finally one column of observed values called "value".

title

Optional title of the dataset

quiet

Should the evaluation text be shown?

Value

An list of class nafta. The list element named "mmkin" is the mmkin object containing the fits of the three models. The list element named "title" contains the title of the dataset used. The list element "data" contains the dataset used in the fits.

Source

NAFTA (2011) Guidance for evaluating and calculating degradation kinetics in environmental media. NAFTA Technical Working Group on Pesticides https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/guidance-evaluating-and-calculating-degradation accessed 2019-02-22

US EPA (2015) Standard Operating Procedure for Using the NAFTA Guidance to Calculate Representative Half-life Values and Characterizing Pesticide Degradation https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-procedure-using-nafta-guidance

Examples

nafta_evaluation <- nafta(NAFTA_SOP_Appendix_D)
#> The SFO model is rejected as S_SFO is equal or higher than the critical value S_c
#> The representative half-life of the IORE model is longer than the one corresponding
#> to the terminal degradation rate found with the DFOP model.
#> The representative half-life obtained from the DFOP model may be used
print(nafta_evaluation)
#> Sums of squares: #> SFO IORE DFOP #> 1378.6832 615.7730 517.8836 #> #> Critical sum of squares for checking the SFO model: #> [1] 717.4598 #> #> Parameters: #> $SFO #> Estimate Pr(>t) Lower Upper #> parent_0 83.755751519 8.076390e-15 76.928220975 90.583282063 #> k_parent_sink 0.001703321 7.452357e-05 0.001108568 0.002617164 #> #> $IORE #> Estimate Pr(>t) Lower Upper #> parent_0 9.685291e+01 NA 8.752855e+01 1.061773e+02 #> k__iore_parent_sink 8.403374e-14 NA 1.092054e-19 6.466412e-08 #> N_parent 6.684458e+00 NA 3.538511e+00 9.830405e+00 #> #> $DFOP #> Estimate Pr(>t) Lower Upper #> parent_0 9.755655e+01 4.439930e-13 8.884447e+01 1.062686e+02 #> k1 4.240633e-02 3.554769e-02 1.414189e-02 1.271610e-01 #> k2 8.237928e-04 2.060933e-02 3.172784e-04 2.138925e-03 #> g 2.881037e-01 1.313715e-04 1.783967e-01 4.299694e-01 #> #> #> DTx values: #> DT50 DT90 DT50_rep #> SFO 407 1352 407 #> IORE 541 5192066 1562968 #> DFOP 429 2383 841 #> #> Representative half-life: #> [1] 841.4096
plot(nafta_evaluation)