thanks for the answers to my question! A short note how I handle the situation. Students use Excel, LibreOffice or a spreadsheet in a symbolic calculator in graphing. However, before spreadsheet they do a fair amount of manual graphing. This is something I'dl like to stress: examine data points carefully to determine whether a straight line or some other fit is appropriate.
In the IB program, the preferred method is not to force a trendline though the origin; the IBO moderators would very likely penalize students if they did the forcing. Instead, some method is used to estimate the uncertainty of y-axis intercept. This can be done using a worst fit line approach - manually or using a spreadsheet - which makes use of error bars in the data, the Linest function in Excel, or the Linreg 2.06 program of Cal Poly Pomona (this is very cool, thanks to John Mallinckrodt!). Knowing an estimate allows the students to determine whether or not the zero is within the uncertainty limits if zero intercept is expected based on the physics of the situation at hand.
Regards,
Antti
--
******************************************************************************************
Viesti on tarkastettu roskapostinsuodatus- ja virustorjuntaohjelmistolla.
Tarkastuksesta huolimatta noudata asianmukaista varovaisuutta liitetiedostoja avatessasi.
******************************************************************************************