Since R_eff is constant, surely all you need to do is multiply R_eff by the uncertainty in alpha?  That will be the uncertainty in delta_R and R_fit.<br><br>The program is only giving you statistically-derived uncertainty for the values it fits; the user needs to determine how to propagate or otherwise deal with this uncertainty.<br>

<br>-Jason<br><br><div class="gmail_quote">On Fri, Nov 16, 2012 at 1:33 PM, Rana, Jatinkumar Kantilal <span dir="ltr">&lt;<a href="mailto:jatinkumar.rana@helmholtz-berlin.de" target="_blank">jatinkumar.rana@helmholtz-berlin.de</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">




<div link="blue" vlink="purple" lang="DE">
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<p class="MsoNormal"><span lang="EN-US">Dear Ifeffit users,</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I have a very simple doubt about reporting the uncertainties in R_fit.</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">In the fit, I have assumed that a bond length changes by a constant fraction, *<b>alpha</b>* such that
</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Delta R = R_effective * alpha</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">and,</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">R_fit = R_effective +/- Delta R</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I can get uncertainties in the fitted value of *<b>alpha</b>* from artemis. But the question is how to work out the uncertainties in the  R_fit. Will it be same as that of *<b>alpha</b>* ??</span></p>


<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks in advance !!!</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">With best regards,</span></p>
<p class="MsoNormal"><span lang="EN-US">Jatin</span></p>
<p class="MsoNormal"><span lang="EN-US"> </span></p>
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