Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Re: Charts or Graphs, and other Excel stuff



Block 1) Assuming the student really doesn't know the difference between
good graphs and bad, take this bull by the horns. Pass out a quiz. Each
item on the quiz shows the same data plotted a few different ways. Ask
which way is best, and why. (This is a tool-independent exercise.)


or one could reading assign relevant sections of Tufte's "The Visual
Display of Quantitative Information".

Some HS instructors have students present their experiments to the
class. You know, expand on their turned in report. Why not instead
have a student present someone else's report? And then grade the
presentation and give it to the experimenter, not the presenter. I
think that would be VERY instructive. This would be a better test of
the "communication" ability of the students than an instructor's grading.


Ideally students would do manual graphing in middle school, so when they
graduate to computers they would know what their graphs should look like.


"For those who are tempted to set up graphing exercises, make
sure you spend some time on how to mislead with graphs. This can be
fun, and also alert the students to bad habits.
Regards,
Jack"

Tufte has numerous examples of lying w/ graphs, chart junk, ducks,
excessive data ink, etc. Some from academic Journals!!!

A quote:

Computers and their affiliated apparatus(es) can do powerful things
graphically in part by turning out hundreds of plots necessary for good
data analysis. But at least a few computer graphics only evoke the
response "Isn't it remarkable that a computer can be programmed to draw
like that?" instead of "My what interesting data." [p.120 op. cit.]

bc, still thinks the invention of the computer was a heuristic mistake.



John Denker wrote:
Edmiston, Mike wrote:

I'm sorry, but people are totally misunderstanding


Certainly I was misunderstanding....


I am not fighting Excel. I am fighting students.


You probably should choose a different verb. Presumably you have
a supportive -- not combative -- relationship with the students.


When I harp at them about this, they typically come back with comments
like, "Well if that's the way a graph is supposed to look, why didn't
Excel do it that way."


That's a very informative comment. That indicates a big problem ...
but a problem that can be solved.

The solution requires two steps. I am a firm believer in the "building
block" approach to learning and teaching.

Block 1) Assuming the student really doesn't know the difference between
good graphs and bad, take this bull by the horns. Pass out a quiz. Each
item on the quiz shows the same data plotted a few different ways. Ask
which way is best, and why. (This is a tool-independent exercise.)

2) Once the students know the difference between good graphs and bad,
then you can answer the crucial question two ways:
Q: "Well if that's the way a graph is supposed to look, why didn't
Excel do it that way."

A1: As to the first clause in the sentence, there is no 'if' about
it. That is not the way a graph should look, and you should
know that by now.

A2: As to the second clause, remember the proverb: It is a poor
workman who blames his tools. You need to take responsibility
for your work. Excel is not in charge of what happens; you
are in charge. Go forth, and make the right things happen!