# Standard error on AWH free energy estimate? **URL:** \ **Category:** User discussions\ **Tags:** awh, free-energy\ **Created:** [May 29, 2022, 8:29pm UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227 "2022-05-29T20:29:31Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![carruthj](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@carruthj](https://gromacs.bioexcel.eu/u/carruthj)\ **Post date:** [May 29, 2022, 8:29pm UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/1 "2022-05-29T20:29:31Z")
Is it possible to get a standard error associated with a free energy estimate with gmx awh similar to what is given by gmx bar? I tried using gmx bar on the dhdl.xvg file and it just spits out a segmentation fault. ---
**Author:** ![pbauer](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pbauer/32/13_2.png) [@pbauer](https://gromacs.bioexcel.eu/u/pbauer)\ **Post date:** [May 30, 2022, 6:37am UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/2 "2022-05-30T06:37:17Z")
Hello, I’m tagging Berk (@hess) here for the general question, but the tool shouldn’t segfault in any case. Can you please open a bug report on Gitlab ([Issues · GROMACS / GROMACS · GitLab](http://gitlab.com/gromacs/gromacs/-/issues)) and tag me (@acmnpv) there? Please also add some example files that reproduce the error. Cheers Paul ---
**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\ **Post date:** [May 30, 2022, 7:13am UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/3 "2022-05-30T07:13:19Z")
No, there is no error estimate for a single AWH run. Since the AWH sampling is time dependent one can not do simple error estimates. A rough error estimate can be obtained by comparing free-energies at different times. But for proper error estimates we recommend running a few indepedent AWH runs. ---
**Author:** ![carruthj](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@carruthj](https://gromacs.bioexcel.eu/u/carruthj)\ **Post date:** [May 30, 2022, 3:39pm UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/4 "2022-05-30T15:39:18Z")
The segfault occurs with both AWH and Expanded Ensemble-generated dhdl files. Perhaps it’s due to the extra thermodynamic state column? ---
**Author:** ![pbauer](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pbauer/32/13_2.png) [@pbauer](https://gromacs.bioexcel.eu/u/pbauer)\ **Post date:** [May 31, 2022, 7:14pm UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/5 "2022-05-31T19:14:22Z")
We will need the input files to check if there is a bug in the tool. Can you please upload them somewhere? Cheers Paul > ![](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/0/02f3f5b37a14cb43ead17c8094443b0d8c72a82e.png "carruthj") | [carruthj](https://gromacs.bioexcel.eu/u/carruthj) > May 30 | > > - | - | The segfault occurs with both AWH and Expanded Ensemble-generated dhdl files. Perhaps it’s due to the extra thermodynamic state column? ---
**Author:** ![carruthj](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@carruthj](https://gromacs.bioexcel.eu/u/carruthj)\ **Post date:** [June 1, 2022, 10:38am UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/6 "2022-06-01T10:38:33Z")
[awhdhdl.xvg](https://gromacs.bioexcel.eu/uploads/short-url/e2KMgOSehsLc5cnuSK77ozGzEdw.xvg) (7.2 MB) [eedhdl.xvg](https://gromacs.bioexcel.eu/uploads/short-url/5447dzgHxF1BhifEfOANqHxIC5m.xvg) (7.1 MB) ---
**Author:** ![hess](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/hess/32/416_2.png) [@hess](https://gromacs.bioexcel.eu/u/hess)\ **Post date:** [June 7, 2022, 9:34am UTC](https://gromacs.bioexcel.eu/t/standard-error-on-awh-free-energy-estimate/4227/7 "2022-06-07T09:34:30Z")
You should not analyze AWH with gmx bar as the data has not been collected at equilibrium. Also not all input required for gmx bar is in the output file. A too late check on the input causes a segmentation fault in gmx bar.