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Re: [Phys-L] Question on data analysis

One should always honor their data. Why would you force it to go through zero? That's backwards. If you have a model that predicts your data should go through zero, then one should look for reasons why it doesn't. Otherwise, why bother acquiring the data in the first place?

Dan Beeker

On May 21, 2015, at 12:00 PM, phys-l-request@www.phys-l.org wrote:

Date: Thu, 21 May 2015 08:50:17 +0000
From: Savinainen Antti <antti.savinainen@kuopio.fi>
To: "phys-l@phys-l.org" <phys-l@phys-l.org>
Subject: [Phys-L] Question on data analysis
Message-ID:
<03A5CDAD2EA0864F9A5E4157AC2EBD945A65E54C@ASGARD-2.istekkipalvelut.fi>
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Hi,

spreadsheet programs usually have a feature which allows to force a trendline through the origin. Of course,
the same thing can be done manually as well. My question is: when it is reasonable to force a trendline through the origin? I mean, a non-zero y-xis intercept may have a physical interpretation or it may indicate systematic error in measurements or (more realistically) may be a combination of both. Given these, what could be a benefit for the forcing of the trendline through the origin?

The question was motivated by an observation that a chemistry colleague insists that her studenst must force a trendine through the origin (in case there is no chemical interpretation, I suppose) for the y-axis intercept.

Regards,

Antti
Finland