Hello everyone, About the matter, I'm currently reviewing the CG7009-DataAnalysis-SF-12Aug2020, and got to the Z-test tool part.
After creating the results table, is possible to insert the variance in their respective cells, but I was looking to the Z-test wiki page referred in the chapter and it says this: "*If the population variance is unknown (and therefore has to be estimated from the sample itself) and the sample size is not large (n < 30), the Student's t-test may be more appropriate.*" I just did a little research on google and found this website doing some explanation about Z-Test: https://www.solver.com/z-test-two-sample-means When running the example in Calc and manually inserting the variances in the cells of the Z-Test results, the output was identical to the example on the website. So I'm guessing that LO Calc should be able to calculate the variance from the given data, and this should be fixed in the software. Or, maybe we can put a note to the user to insert the variances after creating the table. Best regards, Felipe Viggiano Em qua., 2 de set. de 2020 às 07:55, Steve (GMail) < stevemfanning...@gmail.com> escreveu: > Thanks Ilmari and Mark, > > I'm happy to update the section in the 7.0 Calc Guide (which is > currently in preparation) but I'm still confused. Why does the z-test > tool think that the variance of the given data sets is zero? As you say > Ilmari, that is not a number that the user currently enters. > > Regards, > > Steve > > ------ Original Message ------ > From: "Ilmari Lauhakangas" <ilmari.lauhakan...@libreoffice.org> > To: documentation@global.libreoffice.org > Sent: 02/09/2020 11:40:06 > Subject: Re: [libreoffice-documentation] Calc's Z-test tool > > >Thanks! That was my gut feeling. > > > >So the immediate action would be to change the screenshots in Help and > Calc guide so the variance cells have non-zero values, also adding a note > to the instructions. > > > >A further question is, should we consider adding fields for inputting > variance values into the Z-test tool itself? Looking at Microsoft Office > docs, Excel has these. This would become an enhancement request in Bugzilla. > > > >Ilmari > > > >Mark Morin kirjoitti 2.9.2020 klo 2.57: > >>Variance can't be zero for analysis of variance tests (t test, F test, > >>etc). Statistical testing assumes that you have variance otherwise you > >>really wouldn't need a test. > >> > >>On 9/1/2020 4:48 PM, Ilmari Lauhakangas wrote: > >>>I was looking at a bug report again: > >>>https://bugs.documentfoundation.org/show_bug.cgi?id=132983 > >>> > >>>The reporter is scratching their head over the "division by zero" > >>>result for z. > >>> > >>> From what I can see, the "Known variance" values can't both be zero, > >>>if you want to avoid the #DIV/0! results. You have to give at least > >>>one of them a positive non-zero value. > >>> > >>>Now, looking at Help: > >>> > https://help.libreoffice.org/7.1/en-US/text/scalc/01/statistics_test_z.html > >>> > >>> > >>>and the Calc guide chapter CG7009-DataAnalysis-SF-12Aug2020, we see > >>>this same "division by zero" result and the reader is left holding it. > >>> > >>>How to present this better in the docs? I have no experience on the > >>>topic, but I hope we can find some statistician to shed light on this! > >>> > >>>Ilmari > >>> > >> > > > >-- To unsubscribe e-mail to: > documentation+unsubscr...@global.libreoffice.org > >Problems? > https://www.libreoffice.org/get-help/mailing-lists/how-to-unsubscribe/ > >Posting guidelines + more: https://wiki.documentfoundation.org/Netiquette > >List archive: https://listarchives.libreoffice.org/global/documentation/ > >Privacy Policy: https://www.documentfoundation.org/privacy > > > -- > To unsubscribe e-mail to: documentation+unsubscr...@global.libreoffice.org > Problems? > https://www.libreoffice.org/get-help/mailing-lists/how-to-unsubscribe/ > Posting guidelines + more: https://wiki.documentfoundation.org/Netiquette > List archive: https://listarchives.libreoffice.org/global/documentation/ > Privacy Policy: https://www.documentfoundation.org/privacy > -- To unsubscribe e-mail to: documentation+unsubscr...@global.libreoffice.org Problems? https://www.libreoffice.org/get-help/mailing-lists/how-to-unsubscribe/ Posting guidelines + more: https://wiki.documentfoundation.org/Netiquette List archive: https://listarchives.libreoffice.org/global/documentation/ Privacy Policy: https://www.documentfoundation.org/privacy
