Jonathan, Thanks for the link to the standard_name vs. cell_methods discussion. I found some useful discussions in there. It was nice to see others have the same confusion about standard_error being a standard_name modifier (only) while standard_deviation is part of cell_methods. I see [Jonathan indicates](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016332.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtZWV2uQM$ ) the standard error is not in cell_methods because it does not relate to a particular dimension. If this is true then I don't see how we can rely on cell_methods to define uncertainty when standard error is the most common method to estimate uncertainty. This could result in the location of the described method being in two different locations depending (if standard error look in standard_name, if something else look in cell_methods).
I've had a really hard time trying to understand why CF recommends the definition of a statistical process that changes the essence of the values from a mean to standard deviation would use the same standard_name. [Jim points out](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016324.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtuHT_5uU$ ) this is quite confusing, and assumes a person or the software would always need to analyze multiple place of metadata just to determine a value is a standard deviation not the mean or instantaneous value of a value. I think we should keep with [Ken's idea](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016315.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtnkU3rs0$ ) that the standard_name (with modifiers) defines the data and the cell_method is a second order description of what is really in the cells. This is how I have always interpreted the difference. As I go through this email thread I think I should propose my original proposal, which follows along [Jim's idea](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016290.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtTYF_jgo$ ), of using standard name modifiers, and point to cell_methods for information on what sort of operation was performed. This follows [David's interpretation](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016287.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtIsbGbDg$ ) of a standard name modifier as something that further describes a data variable beyond the initial description by the standard name. We could limit the standard name modifier to _total_uncertainty_, _random_uncertainty_, _systematic_uncertainty_ and then expect the users to look in cell_methods for the other details. I'm still concerned with the need [Steve pointed out](https://urldefense.us/v3/__http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2013/016325.html__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtf5Zyqsg$ ) to balance the technically correct description of the values with the ease of use. Since this method will be used by software to discover data and most users will still use an uncertainty estimation when it does not align with their understanding of uncertainty when presented with no other option, we should make the process to discovery a measurement's uncertainty estimation as simple as possible. The other issue I see is that cell_methods (as far as I can tell from the CF document) is used to describe how the values were derived using the other data in the file. So a variable's standard deviation can be simply explained in cell_methods by indicating the dimension the operation was performed over and what statistical process was performed on the data. But this will typically not be how the uncertainty estimate was derived. Most uncertainty estimations will include or entirely contain data that is not part of the provided data file. Or the estimation of uncertainty is provided with an equation from an instrument manufacture that is not just a simple standard error calculation. Trying to put that description of operations in the cell_methods is currently not possible. My program attempted to get an uncertainty estimate for all our primary measurements and present them in a single location. This was a huge task that took many resources to produce. We ended up on a simplified PDF document. As you can see [in the appendix](https://urldefense.us/v3/__https://www.arm.gov/publications/programdocs/doe-sc-arm-17-010.pdf__;!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtx3Wdtsc$ ) there are many different methods used to derive an uncertainty estimation. Many of the estimates are from vendors with proprietary methods they are not willing to share, or are too complicated to put into cell_methods. A majority of the uncertainty estimates are single values. My goal is to just provide a simple method to provide data users with the current best estimate of uncertainty and not bog them down with too much detail. Thanks for the links and discussion, Ken -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://urldefense.us/v3/__https://github.com/cf-convention/cf-conventions/issues/320*issuecomment-902856393__;Iw!!G2kpM7uM-TzIFchu!h3P9Qo9dV16Tb2U5E579epIm5w35N-OjX55POuSGC56GDiuAdK4KhL_n0ThtLBva5JWtBJisfKY$ This list forwards relevant notifications from Github. It is distinct from [email protected], although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to [email protected].
