Saturday, June 16, 2007

I know what the "f" really stands for...

Statistics joke ahead. You have been warned.
Q:How do you graph a linear function?
A: As a straight line—on Cartesian graph paper.
Q:How you you graph an exponential function?
A: As a straight line—on semi-log graph paper.
Q:How do you graph an arbitrary monotonic function f(x)?
A:As a straight line—on f paper!
Zeno told this joke as part of a criticism of people who use unusual axes on graphs of accurate data to mislead people. Examples of how "f paper" works can be found on his post.

The basic idea is that by altering the axes' scales while plotting the data points correctly (according to your scales), you can use the graph to exaggerate or obscure the effect the data measure.

When the human population data is graphed on linear scales, you see an exponential increase in humans in modern times. If you graph that same data on a vertical logarithmic scale, the number of humans seems to grow linearly. If you aren't paying attention to the scale, you could be hoodwinked or even bamboozled.

Of course, some people don't even bother with scales...

3 comments:

astropixie said...

what do you get when you cross a monkey and an elephant?




nothing, they're both scalars.




(boo... hisss.... i know.)

The Fishmonger said...

I'd always heard elephants were vectors-->

What do you get when you cross an elephant with a grape?

Elephant grape sine theta!

What do you get when you cross an elephant with a mountain climber?

nothing, you can't cross a vector with a scalar (scaler)!

(My long time favorite math jokes)

astropixie said...

i have to admit that i never got that one before i saw you write it... scaler... scalar! thanks for clearing that up for me... finally!!