https://support.office.com/en-us/article/f-inv-rt-function-d371aa8f-b0b1-40ef-9cc2-496f0693ac00
https://www.statisticshowto.datasciencecentral.com/probability-and-statistics/f-statistic-value-test/#FandP
https://support.office.com/de-de/article/fvert-funktion-ecf76fba-b3f1-4e7d-a57e-6a5b7460b786
