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help for ^diagtest^                                               (STB-56: sbe36)
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Report summary statistics for diagnostic tests
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    ^diagtest^ testvar diagvar [weight] [^if^ exp] [^in^ range] [^,^ ^prev(^#^)^
                                  ^level(^#^)^ tabulate_options]

^fweight^s and ^pweight^s are allowed; see help @weights@.


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

^diagtest^ displays various summary statistics for diagnostic tests; 
sensitivity, specificity, and predictive values, from a 2x2 table.

^testvar^ is the variable which identifies the result of the diagnostic test,
and ^diagvar^ is the variable which contains the real status of the patient.
Note that the lower category must identify the non-exposed, the negative 
result of the test, or the false status of the patient.


Options
-------

^prev(^#^)^ requests the estimated prevalence, in percentage, of the exposure 
   to provide the positive and negative predicted values based on Bayes' 
   theorem.  The default is the estimated prevalence through the data.

                       (Sensibility x Prevalence)
  PPV = -------------------------------------------------------------
         (Sensibility x Prevalence) + (1-Specificity x 1-Prevalence)


                       (Specificity x 1-Prevalence)
  PPN = -------------------------------------------------------------
         (1-Sensibility x Prevalence) + (Specificity x 1-Prevalence)


^level(^#^)^ specifies the confidence level, in percent, for calculation of
   confidence intervals of the sensitivity, specificity, predictive values,
   and prevalence.  The default is ^level(95)^ or as set by ^set level^.  Note
   that if the ^prev^ option is used the confidence interval is only displayed
   for the sensitivity and specificity values.


Author
------

	Aurelio Tobias
	Universidad Miguel Hernandez
	Alicante (Spain)
	e-mail: bledatobias@@ctv.es


Examples
--------

	. ^diagtest test truediag^
	. ^diagtest test truediag, prev(25)^
	. ^diagtest test truediag, prev(50) chi^
	. ^diagtest test truediag, all^


Also see
--------

 Manual:  ^[R] tabulate, [R] lstat, [R] lsens, [R] lroc^
On-line:  help for @tabulate@, @lstat@, @lsens@, @lroc@