<?xml version="1.0" encoding="utf-8"?><!DOCTYPE article  PUBLIC '-//OASIS//DTD DocBook XML V4.4//EN'  'http://www.docbook.org/xml/4.4/docbookx.dtd'><article><articleinfo><title>FAQ/VarMSE</title><revhistory><revision><revnumber>7</revnumber><date>2015-08-07 10:53:18</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>6</revnumber><date>2015-08-07 10:52:55</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>5</revnumber><date>2013-03-08 10:17:36</date><authorinitials>localhost</authorinitials><revremark>converted to 1.6 markup</revremark></revision><revision><revnumber>4</revnumber><date>2009-03-03 16:14:26</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>3</revnumber><date>2009-03-03 16:14:05</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>2</revnumber><date>2009-03-03 16:12:03</date><authorinitials>PeterWatson</authorinitials></revision><revision><revnumber>1</revnumber><date>2009-03-03 16:11:44</date><authorinitials>PeterWatson</authorinitials></revision></revhistory></articleinfo><section><title>What is the value of the error variance for raw data using that of its scalar transformed data?</title><para>It is sometimes necessary to quote the error variance, or <emphasis>mean square error</emphasis> of scalar transformed responses, such as reaction times, that have very large or small values. In this case the mean square error for the <emphasis>raw</emphasis> data may be obtained from the mean square error for the transformed data by simply multiplying the transformed data's mean square error by the square of the inverse transform.  </para><para>For example let us suppose the data is divided by 1000 and a mean square error for this transformed data is found to be equal to 0.0125. The mean square error of the original data is, therefore, equal to 1000<superscript>2 </superscript> times the mean square error of the transformed data  = 10<superscript>6 </superscript> x 0.0125 = 12500.    </para></section></article>