help for ^diagtest^

Report summary statistics for diagnostic tests ----------------------------------------------

^diagtest^ testvar diagvar [weight ^if^ exp ^in^ range][, ^prev(^#^)^ ^level(^#^)^ table_options]

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(^#^)^ request the estimated prevalence, in percentage, of the exposure to provide the positive and negative predicted values based on the Bayes' theorem. Default is the estimated prevalence thorough 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. Default is the 95%. Note that if the ^prev^ option is used the confidence interval is only displayed for the sensitivity and specificity values.

Author ------

Aurelio Tobias Medical Statistician Getafe (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@