Saturday, September 08, 2012

Zero Point

On the Dinocrat site, via Maggie's

One of my favorite deceptions to point out WRT graphs. As we are talking about millions of people and long-term trends, this drop in participation may indeed be alarming. It is a four-point drop in how many of us are gainfully employed, after all. But the zero-point of this graph is 63.5, and the hundred-point is 67.5, exactly the size of the change, not 0-100 percent. Visually, it tells us that nearly everyone worked twelve years ago and now, no one does.

Naughty, naughty.


Sponge-headed ScienceMan said...

"it tells us that nearly everyone worked twelve years ago and now, no one does."
AVI, not if take the trouble to read the X and Y labels like you should (you know, like Gerry not reading the beer bottle label and pouring himself a glass of hard cider instead!

james said...

It would be amusing to plot (similarly zero-suppressed) the number of people in the work force age group on the same plot. Then you'd be comparing apples to apples, and probably getting a much more dramatic graph, since the potential work force is almost certainly growing.

Of course the figures don't account for illegal workers, so they require some salt anyhow.

karrde said...

When you want to show the change as big, put the lower value as close to the bottom of the graph as possible.

When you want to show the change as small, put the bottom of the graph at "0".

It should be elementary. But instead, it is rather advanced. (I learned about this trick while perusing portions of a college-level textbook.)

Gringo said...

There is another way of looking at the truncated graph issue. With limited space, one wants to make optimal use of the space. Leave out the "dead" parts of the graph, as it were.

It is not not necessarily done for the sake of deception.

It would be interesting to do a "survey group" reaction to the graph.

Sponge-headed ScienceMan said...

You know, the trend on this graph reminds me a little too much of my 401k account. But I'm glad it's not at zero (my account that is).

Mark Stoler said...

You highlighted a pet peeve of mine. I used it in a blog post and added another example I encountered several years ago.