Statistical methods in epidemiology. VIII. On the use of likelihood ratios for diagnostic testing with an application to general practice.
OBJECTIVE
An array of statistical methods is available for 2 x 2 contingency table analysis. These include odds ratios, reliability coefficients and the Chi-squared test. This paper continues the '2 x 2' theme but extends it to look at diagnostic testing. The setting is primary care, the disease is urological cancer.


METHODS
Several statistical indices are discussed to measure diagnostic efficiency; these include sensitivity, specificity and the likelihood ratio. The latter can be converted into a flexible 'weight of evidence', which is equivalent to the naive Bayes' discriminant.


RESULTS
The utility of the naive Bayes' discriminant is illustrated in a primary care setting.


CONCLUSIONS
The naive Bayes' discriminant has proved to be the most durable of statistical discriminants in medical diagnosis. The reason for its durability is ease of use. Despite a concern about independence, it remains a popular choice as a diagnostic aid.
Rigby
Alan S
AS
Academic Department of Cardiology, University of Hull, Kingston-Upon-Hull, UK. asr1960@hotmail.com
Summerton
Nick
N
D000368:Aged; D001499:Bayes Theorem; D003657:Decision Making; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011320:Primary Health Care; D012680:Sensitivity and Specificity; D014571:Urologic Neoplasms / Q000175:diagnosis*