UNC-BMElab MPN Calculator

This website contains information on the calculation of  Most Probable Numbers (MPN) for the enumeration of micro-organisms in water samples.

MPN Equations
The following document contains the equations used to calculate an MPN as well as the
upper and lower confidence bounds.  Links to references in PDF format are included where
available.

Download a typical MPN Table here (for IDEXX QT 2000):  MPN Lookup Table

Programs for Automatic MPN Calculation
MATLAB:  Several programs are available that will allow you to calculate the MPN and upper and lower bounds
The following functions are available for download for the Matlab Programming Platform.  If
you need assistance on obtaining Matlab and getting started with these functions, please see the tutorials in
the next section.

Matlab Function 1:  Background Function with MPN Equations to calculate MPN and bounds (called calcmpn.m)
Matlab Function 2:  User Function for calculating MPN (called MPNcalculator.m)

R:  The following functions are available for download for the R Programming Platform.  If you need assistance on
obtaining R, please see the R Tutorials below.

R Function 1:  Calculate MPN
R Function 2:  Calculate MPN with Input File

Tutorials
MATLAB:  Download the following tutorials to guide you through the use of the MPN calculator in Matlab.
You should also download Function 1 and Function 2 before beginning any tutorial.
Downlad the sample data for Tutorial 2 & 3 here:  Sample Data

Tutorial 1:  New to Matlab?
This tutorial will show you how to obtain Matlab and do simple tasks such as create a variable,
call a function, and display output

Tutorial 2:  Using the MPN Calculator with Default Parameters
This tutorial will show you how to use the MPNcalculator function in Matlab, starting from an
original Excle file and using the function's default parameters

Tutorial 3:  Using the MPN Calculator with User Defined Parameters
This tutorial will expand upon the second tutorial and show you how to create input parameters for the
MPN calculator.

R:   Download the following tutorials to guide you through the use of the MPN calculator in Matlab.
You should also download Function 1 and Function 2 before beginning any tutorial.
Downlad the sample data for Tutorials here:  Sample Data 1  Sample Data 2

Tutorial 1:  New to R?
This tutorial will show you how to obtain Matlab and do simple tasks such as create a variable,
call a function, and display output

Tutorial 2:  Using the MPN Calculator with Default Parameters
This tutorial will show you how to use the MPNcalculator function in Matlab, starting from an
original Excle file and using the function's default parameters

Tutorial 3:  Using the MPN Calculator with User Defined Parameters
This tutorial will expand upon the second tutorial and show you how to create input parameters for the
MPN calculator.

Duplicate Samples
Download the following lookup table to calculate the MPN and associated 95% confidence bound.
Put the number of positive small and large wells for 1st and 2nd samples in the first sheet.

Lookup Table:  The MPN Calculator for duplicate samples