I’ll confess that I’m strongly anti-sigfigs. My problem with sigfigs are the following:
– I have never met a scientist or engineer who uses sigfig rules in their daily practice or in scientific communication. My understanding is that sigfigs are a staple of “school science”, in much the same way, “the scientific method” is. Based on my experience, sigfigs are typically used in a way as to mispresent scientific practice and thinking.
– They are just rules to follow, which can be followed mindlessly. Perhaps, they are or were intended to cultivate habits for thinking about uncertainty and precision, but I have found that they almost always invoke authoritative non-sense from students.
– Thinking about spread in data and uncertainty in the determination of quantities does not require the complexity of std dev, nor the formalism of +/- notation, nor the mindless routines of sigfigs. For example, ranges can be talked about and represented graphically. I want to cultivate the thinking behind and along with the increasingly sophisticated routines we use, but only as they become relevant to the increasingly challenging practices we carry out.
– Most college professors (that I have met) who relentlessly deduct points for sigfigs also do not have meaningful criteria for evaluating the quality of student scientific work, practice, and thinking. The way I see it, many of these professors need some way of creating a spread in their grades and deductions like “sigfigs” and “units” are an easy out, which they can also defend on the basis that they reflect important scientific thinking. I’m not saying the thinking behind uncertainty or units isn’t important–I’m saying that sigfigs is for a poor proxy of scientific thinking and habits of mind, and that relentless grading of sigfigs often comes as the expense of meaningful assessment and feedback.
— Sigfigs are wholly un-generalizable, because they do not cultivate the right thinking or appreciation for their purpose. Students are left helpless when thinking about anything beyond the rules– for example what would such students do when they have uncertainty in an angle and they have to take the sine or cosine or tangent of that angle, or take the reciprocal of some quantity such as frequency and period.
As an added note, this post was inspired by this weel’s Global Physics Department for readers who aren’t aware. This Wednesday (8/10/11) we’ll be discussing various ways to teach error propagation.
This is the “corkboard” we’ve been using to brainstorm ahead of the meeting: