Understanding Data - Data Points: Visualization That Means Something - page 375

If you were to pour all the gumballs on to the table and count every one, you
wouldn't have to guess because you would get the full tally.

But say you can grab only a handful,
and you have to guess the contents of
the entire jar, based on what you have
in your hand. A larger handful would
make it easier to guess because it's
more likely a better representation
of the entire jar. On the other side of
the spectrum, you could take just one
gumball out, and it'd be much harder
to guess what else is in the jar.

With one gumball, your margin of
error would be high; with a large
handful of gumballs, your margin
of error would be lower; and if you
counted all the gumballs, you would
have zero margin of error.

Apply that to millions of gumballs in
thousands of differently sized jars,
with different distributions and big
and small handfuls, and estimation

FIGURE 1-22 Household estimates in 2010

FIGURE 1-23 Gumballs and margin of error