Object Reference : Object View and Procedure Reference : Equation
Estimation by stepwise least squares.
eq_name.stepls(options) y x1 [x2 x3 ...] @ z1 z2 z3
Specify the dependent variable followed by a list of variables to be included in the regression, but not part of the search routine, followed by an “@” symbol and a list of variables to be part of the search routine. If no included variables are required, simply follow the dependent variable with an “@” symbol and the list of search variables.
method = arg
Stepwise regression method: “stepwise” (default), “uni” (uni-directional), “swap” (swapwise), “comb” (combinatorial).
nvars = int
Set the number of search regressors. Required for swapwise and combinatorial methods, optional for uni-directional and stepwise methods.
Weight series or expression.
Note: we recommend that, absent a good reason, you employ the default settings Inverse std. dev. weights (“wtype=istdev”) with EViews default scaling (“wscale=eviews”) for backward compatibility with versions prior to EViews 7.
wtype=arg (default=“istdev”)
Weight specification type: inverse standard deviation (“istdev”), inverse variance (“ivar”), standard deviation (“stdev”), variance (“var”).
Weight scaling: EViews default (“eviews”), average (“avg”), none (“none”).
The default setting depends upon the weight type: “eviews” if “wtype=istdev”, “avg” for all others.
Specify the name of the coefficient vector (if specified by list); the default behavior is to use the “C” coefficient vector.
Force the dialog to appear from within a program.
Print estimation results.
Stepwise and uni-directional method options
Set stepwise or uni-directional method to run backward. If omitted, the method runs forward.
Use t-statistic values as a stopping criterion. (default uses p-values).
ftol=number (default = 0.5)
Set forward stopping criterion value.
btol=number (default = 0.5)
Set backward stopping criterion value.
fmaxstep=int (default = 1000)
Set the maximum number of steps forward.
bmaxstep=int (default = 1000)
Set the maximum number of steps backward.
tmaxstep=int (default = 2000)
Set the maximum total number of steps.
Swapwise method options
Use minimum R-squared increments. (Default uses maximum R-squared increments.)
Combinatorial method options
Suppress the warning message issued when a large number of regressions will be performed.
eq1.stepls(method=comb,nvars=3) y c @ x1 x2 x3 x4 x5 x6 x7 x8
performs a combinatorial search routine to search for the three variables from the set of X1, X2, ..., X8, yielding the largest R-squared in a regression of Y on a constant and those three variables.
See “Stepwise Least Squares Regression”.