QUB Logo Excel-Based Plasmid Fitter

A robust fitter for analysing plasmid gel electrophoresis results has been implemented in Excel, making use of its Solver add-in to provide non-linear regression facilities.

This fitter makes use of dose-response equations which have been derived from rate equations describing the plasmid system, with the goal of providing a more robust method than those in common use, which uses a variety of approximations to allow for the use of linear regression.

This improvement takes on two forms: Firstly, the move to dose-response equations which are based directly on the behaviour of the plasmid system in response to radiation provides a reduction in the systematic errors which result from the approximations made in defining the dose-response curves.

Secondly, this method has been developed to allow fitting to all of the parameters simultaneously, rather than using a single type of plasmid to analyse each type of strand breaking. This offers the potential for a significant reduction in the amount of uncertainty in the fitted parameters, as it makes a more complete use of the data.

A more complete description of the underlying mechanisms of the fitter, as well as verification of its accuracy, will be completed soon.

Downloads

The fitter can be downloaded here, and installation and usage notes are also available.

The fitter has been prepared in Office XP under Windows, and has been tested for forward compatibility with Office 2003 and 2007. It should require no additions to the basic Excel installation, but the Solver Add-in must be activated to make it available to the fitter.