The parameter estimates and the Hougaard measures of skewness were obtained by using the NLIN
procedure of the SAS (SAS, 2006), in which the Hougaard measures of skewness were calculated by the following expression
the change-point), and we fitted the model to the data with nonlinear least-squares estimation (the NLIN
procedure in SAS, vers.
This was accomplished by performing nonlinear regression analyses using the NLIN
procedure in the Statistical Analysis System package (SAS version 9.
Once the type of functional response was determined, data were fit to the mechanistic model and the random predator equation, and handling times and attack constants were estimated (PROC NLIN
, SAS Institute 2003).
An iterative least squares procedure using NLIN
(SAS Institute, Inc.
The exponential regression was fitted to the model using the SAS NLIN
procedure for nonlinear regression (SAS Institute Inc.
The parameters were first estimated using a non-linear regression model (PROC NLIN
, SAS/STAT [R] software).
We compared the weights of each exposure group by fitting the quadratic weights curves for each rat using PROC NLIN
(SAS Version 8.
h]) and attack rate (a') parameters which were estimated using nonlinear least square regression based on the proportion of prey eaten (Na/N0) as a function of initial prey densities (N0) (PROC NLIN
, SAS Institute 2002).
1) to (4)) were estimated with the NLIN
procedure of SAS.
A non-linear modelling technique (SAS NLIN
Proc) was used to fit the relationship between soil strength and volumetric water content using the residual of mean square (RMS) as a model selection criterion.
Results for NLIN
join point age estimates for the top and bottom sections of each tree are given in Table 2.