Make sensitivity analysis plot(s) for current box:

sens (pltvar="", miss=T, span=0.3, nc=2, ln=F, qtl=0.1, minsmu=11)

Optional arguments:

   pltvar="name"/number of input variable to be plotted.
       Must be a variable defining current box.
       If missing, then all variables defining box are plotted.
   miss = T/F => do/don't show missing values on real variable plots.
   span = LOESS smoother span for real variable plots.
   nc = number of columns in plot matrix. Ignored if pltvar is specified.
   ln =T/F => do/don't show x-axes on log scale for real variable plots.
   qtl = quantiles for abscissa hash marks on real variable plots.
   minsmu = minimum number of distinct abscissa values to invoke smoother
            (LOESS) on real variable plots.  

Examples:

   sens()
   sens(5)
   sens("age")
   sens(miss=F,span=0.5,ln=T)

Remarks:

   The formats of the sensitivity analysis plots are described in Friedman and
   Fisher (1997) Section 16.1.

   The boundaries of the current box can be modified by responding to the
   SuperGEM dialog window prompt

      Modify box {>sens()}.
      var.  [value  [limit (l | u)]] (<cr> = no/done)

   A null response (<cr>) implies no (further) changes are to be made.

   The entry var. can either be the number or character name of an input
   variable.  If this is the only entry on the response line, then that
   variable is removed from the definition of the box.

   The (optional) second entry (value) can either be a number, or the character
   m or M indicating missing value. If the entered variable is categorical,
   or the entered value is m or M, the modification that takes place 
   depends on whether or not that variable value is included in the current
   box. If it is, then it will be removed from the box; if not, then it will
   be added to the box. If the entered variable is real valued, then the box
   is modified so that its LOWER limit on the entered input variable is
   changed to the entered value.

   If the entered variable is real valued, then an (optional) limit flag
   can also be entered. It has two possible character values (u or l).
   The value u indicates that the upper box boundary on the entered variable
   is to be changed to the entered value. The value l indicates the lower
   boundary, and has the same effect as if the limit flag were not entered.

   Examples of possible response sequences are:

      2
      edu
      occup 6
      4 m
      age 25
      age 50 u

   The box boundaries can be repeatedly modified (one at a time) by repeated
   responses to the (Modify box) prompt in the SuperGEM dialog window. When
   no further modifications are desired, a carriage return (<cr>) is entered.
   
   It is strongly recommended that sensitivity plots for all variables be
   remade after each individual modification. Modifying the boundary on one
   input variable changes the plots on all of the others. This is done by
   by entering sens() at the S command prompt (>) in the S command window
   after each change is entered in the SuperGEM window.

   As an aid to determining appropriate modification values, the S command
   locator() can be entered at the S command prompt(>). [See help(locator).]
   The locator() command applies to the last plot produced. If this plot does
   not represent the variable (var) of interest, then enter sens(var) at the
   S command prompt. This produces the corresponding sensitivity plot for just
   the variable var.