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jono90one
United Kingdom
2 Posts |
 Posted - 12/12/2010 : 05:25:13 AM
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I have a graph of force against extension, but the uncertainties vary for some of the values, so i wanted to calculate the min slope, max slope then mean slope. Then i can calculate a good spring constant and hence uncertainty for that.
Not entirely sure if when you select "Fit linear with x" in the analysis column that it does this automatically. But when i go to differentiate i get no uncertainty (And I can't calculate it manually because I do not know what the min/max slopes are).
Hope you can help me :)
Thanks.
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jono90one
United Kingdom
2 Posts |
Posted - 12/12/2010 : 1:18:29 PM
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| Any ideas? Just got to hand this in tomorrow :D |
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easwar
USA
1964 Posts |
Posted - 12/13/2010 : 11:35:27 AM
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Hi,
Are you fitting data with X error bars? If yes, and if you are therefore using the Analysis->Fit Linear with X Error tool, then that tool only provides error on parameters, it does not provide upper and lower confidence levels on the parameters.
If instead you have Y error bars and not X error bars, then if you use the Analysis->Fitting->Linear Fit tool, under the Quantities to Compute->Fit Parameters node in the dialog, check the LCL and UCL check boxes. These will then give you upper and lower confidence values on slope and intercept. You could then use those values are your min and max slope, and the parameter value as the mean value, to do the computation you are looking for?
Easwar
OriginLab
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Mean slope?