EPR-Val Test Pack 2 Web browser version. This calculator works off-line. (IE4)

Enter data into the boxes "A","B","C",and "D"
Test condition
Present Absent
(A+C) (B+D)
Test for condition. Read code +ve or -ve Present A+B= A (true pos)= B (false pos)=
Absent C+D C (false neg)= D (true neg)=
Total A + B + C + D =
Sensitivity = %
Specificity = %
Liklihood ratio for positive test result =
Liklihood ratio for negative test result =
Positive predictive value = % 95% CI= %
Negative predictive value = % 95% CI = %
Accuracy = %
Prevalence = %
Pre-test odds +ve =
Post-test odds +ve =
TPFN ratio =
DBF ind 10,000

Toolkit for measuring the validity and utility of general practice electronic patient records.

Reference BMJ 2001;322:1401-1405 ( 9 June ) Information in practice A survey of validity and utility of electronic patient records in a general practice. Alan Hassey, general practitioner, David Gerrett, senior research fellow, Ali Wilson, senior associate lecturer. HTML programme auther David J R Hutchon BSc, MB, ChB, FRCOG Consultant Gynaecologist, Memorial Hospital, Darlington, England. Based on the EPR-val XL spreadsheet test pack written by Dr Alan Hassey.
You are welcome to keep this page and use the calculator off-line. Any comments are welcome. E-mail to me at DJRHutchon@Postmaster.co.uk

Statistics - Calculations

Sensitivity = truepositives/diseasepositive [A/(A+C)]
specificity = truenegatives/diseasenegatives [D/(B+D)]
LR+ = Sensitivity/(1-Specificity)
LR- = (1- Sensitivity)/Specificity
PPV =
NPV =
Accuracy =
Prevalence =
Pretest odds + =
Post-test probability + =
TPFN ratio =
DBFind 10,000 =

Statistics - definitions

Sensitivity Chance of having a positive test in patients with the test condition
Specificity Chance of having a negative test in patients without the condition
LR+ve Ratio of probability that patient with test condition has a positive test result to the probability that a patient without the condition has a negative test result
LR-ve Ratio of probability that patient with test condition has a negative test result to the parbability that a patient without the condition has a negative test result
PPV Chance of having test condition given a negative test result
NPV Chance of not having test condition given a negative test result
Accuracy The proportion of all tests that are correct
Specificity Chance of having a negative test in patients without the condition
Prevalaence True positives plus false negatives for the test condition as proportion of population
Pre-test odds/probability The odds/probability of the condition (prevalaence) in the whole community
TPFN ration The proportion of true positives to false negatives for the test condition
DBFind 10,000 The number of false negative cases in a database od 10,000 patients