Monday, March 25, 2013

Age of the Oldest Person You Know

From a Prudential TV commercial that has people place large, round stickers on a number line to represent the age of the oldest person they know. This forms a histogram or dotplot. The message is to have Prudential prepare you to have adequate money for all these years. You can add your own sticker at the Prudential website. Here is a video behind the scenes.

Monday, March 18, 2013

Top of the Curve = Middle of the Pack

Here's a normal distribution design from a t-shirt (thanks Jun). Unlike the possible confusion we have seen from bell-curve t-shirts, this one, from shirtwoot! shows that the designer got the bell-curve's relation to the normal distribution correct. The bell-curve is not the normal distribution. The bell-curve only describes the normal distribution. The normal distribution is a specific random arrangement of measurements on a number line. This arrangement ranges from small measurements on the left of the number line, up to large measurements on the right. The curve represents the frequency or density of observations along the line. Where the curve is low, the observations have a very low density. We would expect few measurements there, occurring sparsely in those regions. Where the bell-curve is higher, we expect a dense arrangement, with observations piling up to a peak in the middle. But the location of this peak on the bell-curve lies in the middle of our number line range. The peak corresponds to the measurement that occurs most often, where its measurement is most common. It is literally the peak of mediocrity.

This shirt design gets it right. At this peak, you have not surmounted all around you to become the best. On the contrary, you've truly "reached mediocrity".

Monday, March 11, 2013

More Cumulative Distribution Tabs

This is a recent post from Shorpy.com, a blog of vintage photographs. This image from 1933 shows a woman deftly gluing alphabet tabs on, what appears to be, a dictionary. We've seen earlier how such tabs represent the cumulative distribution function of the first letter of the words in English. The close-up below show the dictionary to the woman's left. The tabs for letter groups run from Z to A from left to right. For our use, we flip it over allowing the alphabet to run properly from A to Z.
The tabs then show relatively few English words beginning with the last letters of the alphabet.
When flipped over, we can see the tabs form cumulative distribution function just as the printed pages showed in our earlier post. More details on these cumulative distribution images can be found in my paper available here.

Monday, March 4, 2013

Market Price

Market Price (getmarketprice.com) collects the current prices of items (over $100) selling on e-bay. It provides summary statistics (min, max, median, mean, and standard deviation) along with a histogram of prices and a scatterplot of  time left to bid against price. They also include a list of the raw data with links.