one of c("beta1", "beta2", "a.x", "a.c", "b.c", "SAM", "AS",
"SSDO", "circ.diff") to indicate for which parameter a traceplot is
required. beta1 and beta2 are the linear intercepts and
coefficients of the first and second component. circ.diff are the
circular differences with the intercept on the outcome variable for the
different levels of categorical variables.
variable
a character string with variable name(s) to indicate for
which variable(s) a traceplot is required.