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Hi all,
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<div class="">I am fitting an equation to data that has quite large errors at one end of the measuring range and considering the error estimates is essential to getting good results. A problem is, however, that it seems fitting always assumes symmetric errors.
My y-values are volume fractions, which obviously cannot be greater than 1, but as I approach volume fraction 1, my estimated errors are on the order of 0.2 or 0.3. This means that a value of 0.9 is considered going from, say, 0.7 to 1.1 during fitting, but
of course values greater than 1.0 do not make sense.</div>
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<div class="">In another data set, I have x-values that I know are lower estimates. In other words, here I would like to set x-error downwards equals zero but the error upwards can be significant. I can plot the data with asymmetric error bars, but I cannot
find a way to tell the fitting algorithm to consider asymmetric errors. </div>
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<div class="">Am I missing something here, or did I misunderstand something fundamental about how the fitting works, or can I tweak the fitting so asymmetric errors are being considered?</div>
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<div class="">Thanks a lot!</div>
<div class="">/Jan</div>
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<div style="margin: 0in 0in 0.0001pt;" class=""><span style="letter-spacing: 0px; font-family: Arial; font-size: 10px;" class=""><br class="Apple-interchange-newline">
Dr. Jan P. F. Lagerwall </span></div>
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<span style="letter-spacing: 0px; font-style: normal; font-size: 8px;" class=""><font face="ArialMT" class="">Department of Physics and Materials Science</font></span></div>
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<span style="letter-spacing: 0px;" class="">Université du Luxembourg</span></div>
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T +352 46 66 44 6219</span></div>
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66 44 36219</span></div>
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<span style="letter-spacing: 0px;" class=""><a href="mailto:Jan.Lagerwall@uni.lu" class="">Jan.Lagerwall@uni.lu</a></span><span style="letter-spacing: 0px; color: rgb(0, 0, 0);" class=""> /</span><a href="http://www.lcsoftmatter.com" class="">www.lcsoftmatter.com</a></div>
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<a href="http://physics.uni.lu" class="">physics.uni.lu</a>, <a href="http://www.uni.lu" class="">
www.uni.lu</a></div>
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