Test page 2

Test page 2

Written by Ronny Gunnarsson and first published on January 10, 2019.
Last revised on October 15, 2023.

This web-page is used by the site administrator for testing purposes. Please ignore this page.

Calculator for EPV
Version 1.12 Revised: 2001-12-10

You can calculate Etiologic Predictive Value (EPV) by entering:

The sensitivity of the test.
Theta, i.e. the relation between the proportion of positive tests in a healthy control population and in a population of symptomatic carriers. The value 1.0 is suggested and will be appropriate for most situations.
The number of positive and negative tests obtained in the group of symptomatic patients.
The number of positive and negative tests obtained in a healthy control population.

The numbers already filled in is an example of evaluating a throat culture used during summer season in children 3-15 years of age¹. Press “Calculate” to see EPV being calculated. Then alter the numbers to fit your situation and press “Calculate”.


1.	Set the preconditions for the calculation
	Sensitivity of the test to discover the marker it is designed to detect (must be >0 and <1)
	Theta, i.e. the relation between the proportion of asymptomatic and symptomatic carriers. Theta must be >0. For more information on theta click on FAQ in the menu to the left (if you do not see a menu to the left click on “Back to Main menu” at the bottom of this page).

2.	Fill in the number of positive and negative tests among patients and the healthy comparison group
			Symptomatic patients	Healthy individuals
Positive test T+
Negative test T-

3.	Calculate Etiologic Predictive Value (EPV) by pressing the button


4.	View and interpret the result
Warning messages:
		Estimation	95% confidence interval
	Positive-EPV:
	Negative-EPV:

Enter what you want to find and click OK Search