Excel

Note: Excel is a spreadsheet and not a scientific graphing application. CLASSE-IT recommends looking at dedicated plotting tools for accurate data analysis.

Issues known to CLASSE-IT are documented here, with any work arounds known linked or documented here.

Chart trendline formula is inaccurate in Excel

Microsoft provides documentation on this issue:
https://learn.microsoft.com/en-us/office/troubleshoot/excel/inaccurate-chart-trendline-formula
We recommend you make the suggested changes if you need accurate trendlines in Excel.

Excel automatically changes numbers to dates

https://support.microsoft.com/en-us/office/stop-automatically-changing-numbers-to-dates-452bd2db-cc96-47d1-81e4-72cec11c4ed8