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help for ^rocsize^                                                (version 1.0.0)
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Power for one sample screening study - continuous data
------------------------------------------------------

    ^rocsize^ tp_rate fp_rate, ^nd(^#^)^ ^ndb(^#^)^ ^tpn^ull^(^#^)^ ^fpn^ull^(^#^)^
         [^,^ ^a^lpha^(^#^)^ ^ns^im^(^#^)^ ^d^ots ^nodis^play ^kern^al^(^kernal name^)^
          ^kwid^th^(^#^)^ ^res^file^(^filename^)^ ^replace^]


Description
-----------

^rocsize^ determines power to detect ROC curve improvement relative to the
   binormal ROC defined by the joint fixed null true (^tpnull(^#^)^) and false
   positive (^fpnull(^#^)^) rates for a sample drawn from a population with
   binormal ROC defined specified alternative rates (^tp_rate^ & ^fp_rate^) and
   specified sample sizes for diseased (^nd(^#^)^) and non-diseased (^ndb(^#^)^)
   subjects.

   Power is based on rejection of the null (tpr_0, fpr_0) relative to the
   one-sided upper confidence bound for the fpr(at tpr_0) and/or lower bound
   for the tpr(at fpr_0) for simulated samples.

   Null and alternative true and false positive rates should be specified as
   numbers between zero and one.

   returned results (power):
     r(pow_w1) based on Wald interval rejection; roc(fpr_0) lower bound > tpr_0
     r(pow_w2)   "    "  "       "        "      fpr(tpr_0) upper bound < fpr_0
     r(pow_w3)   "   on rejection per either of the above
     r(pow_l1), r(pow_l2), r(pow_l3) as above, but using logit(roc) based
                confidence interval rejection

Options
-------

^nsim(^#^)^ specifies the number of simulated study samples to be drawn for
   determination of power.  The default is 500 samples if not otherwise
   specified.

^alpha(^#^)^ specifies the type I error rate.  the default is
   1 - ($S_level/100.), i.e. .05 if the level has not been set.  See @level@

^nodisplay^ suppresses output display (in case where only returned results are
    desired).

^dots^ optionally displays a dot on the screen for each simulated sample drawn.

^kernal(^kernal name^)^ specifies the kernal option for the kernal density
    calculation used in computing the confidence bands.  This is passed to the
    kdensity command.  see help ^kdensity^.  By default the Epanechnikov density
    is used.

^kwidth(^#^)^ specifies the halfwidth of the kernal, the width of the density window
    around each point.  See ^[R] kdensity^ regarding the default "optimal width".

^resfile(^filename^)^ creates a Stata file (^.dta^ file) with the simulation
    results.

^replace^ requests that if an existing file is specified for saving simulation
    results it should be overwritten.


Remarks
-------

Persons interested in reproducibility of results should set the random-number
seed by typing set seed # before running ^scrtest^; see help @generate@.

Simulated samples generated under the alternative (tpr_1, fpr_1) hypothesis are
drawn from

    Y_dbar ~ N(0,1) and Y_d ~ N(mu,1)

  where

    mu = PHI_inv(1-fpr_1) + PHI_inv(tpr_1)


Author
------

        Gary Longton, Fred Hutchinson Cancer Research Ctr.
        glongton@@fhcrc.org


Also see
--------

 On line: help for @roctab@,  @emroc@ if installed,
          @scrsize@ if installed, @aucsize@ if installed,
