Based on a nonlinear model, the dependent variable of a certain equation is predicted by two independent variable, i.e., .independent_1 and .independent_2 including their higher-order terms.
doSurfaceAnalysis(
 .object             = NULL,
 .alpha              = 0.05,
 .dependent          = NULL, 
 .independent_1      = NULL,
 .independent_2      = NULL,
 .n_steps            = 100
 )An R object of class cSEMResults resulting from a call to csem().
An integer or a numeric vector of significance levels.
Defaults to 0.05.
Character string. The name of the dependent variable. Defaults to NULL.
Character string. The name of the first independent variable. Defaults to NULL.
Character string. The name of the second independent variable. Defaults to NULL.
Integer. A numeric value giving the number of steps, e.g., in
surface analysis or floodlight analysis the spotlights (= values of .moderator)
between min(.moderator) and max(.moderator) to use. Defaults to 100.
A list of class cSEMSurface with a corresponding method for plot().
See: plot.cSEMSurface().