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.

Print nafta objects. The results for the three models are printed in the order of increasing model complexity, i.e. SFO, then IORE, and finally DFOP.

```
nafta(ds, title = NA, quiet = FALSE, ...)
# S3 method for nafta
print(x, quiet = TRUE, digits = 3, ...)
```

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

- 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?

- ...
Further arguments passed to

`mmkin`

(not for the printing method).- x
An

`nafta`

object.- digits
Number of digits to be used for printing parameters and dissipation times.

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.

```
nafta_evaluation <- nafta(NAFTA_SOP_Appendix_D, cores = 1)
#> 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 83.7558 1.80e-14 77.18268 90.3288
#> k_parent 0.0017 7.43e-05 0.00112 0.0026
#> sigma 8.7518 1.22e-05 5.64278 11.8608
#>
#> $IORE
#> Estimate Pr(>t) Lower Upper
#> parent_0 9.69e+01 NA 8.88e+01 1.05e+02
#> k__iore_parent 8.40e-14 NA 1.79e-18 3.94e-09
#> N_parent 6.68e+00 NA 4.19e+00 9.17e+00
#> sigma 5.85e+00 NA 3.76e+00 7.94e+00
#>
#> $DFOP
#> Estimate Pr(>t) Lower Upper
#> parent_0 9.76e+01 1.94e-13 9.02e+01 1.05e+02
#> k1 4.24e-02 5.92e-03 2.03e-02 8.88e-02
#> k2 8.24e-04 6.48e-03 3.89e-04 1.75e-03
#> g 2.88e-01 2.47e-05 1.95e-01 4.03e-01
#> sigma 5.36e+00 2.22e-05 3.43e+00 7.30e+00
#>
#>
#> DTx values:
#> DT50 DT90 DT50_rep
#> SFO 407 1350 407
#> IORE 541 5190000 1560000
#> DFOP 429 2380 841
#>
#> Representative half-life:
#> [1] 841.41
plot(nafta_evaluation)
```