Footsie?

Distributions of foot placement, sitting on a bench, in a casino "on the Boardwalk in Atlantic City"

Old School Rules: A Normal Slide Rule

Here's a normal slide rule. Yes, it's very old technology, but it helps to see some workings that other high-tech black boxes hide.
Of course you can even get much more extensive stat calculators for your IPhone See StatsMate. Still this is fun.


Find the BIG TIF file at this link (or click on the illustration below). And, as requested, here is a smaller pdf version. Print it out on heavy card stock.


Cut off the slider on the left and set it aside. On remaining front section, cut out the normal curve and the results window. Fold back the top and bottom. Then slide in the slider with the numbers down and the blue rectangle up.
Pick your z-score and read the area of the blue shaded region.

Data Jewelry

Here is a novel data representation, high and low temperatures over the course of a year are laser-cut into small house-shaped slices that encircle the bracelet. Also shown are small circular holes with area proportional to the monthly rainfall. A flattering year's worth of weather data to wear on your wrist. See details here.

Time Series Heat Map in R

The Revolutions blog gives information on the statistical programming language R. Heat maps are shown in a recent post. A calendar is displayed horizontally with days of the week in rows and months arranged in jagged columns (since not all months have the same number of days). A color is plotted on each month's day for the magnitude of a time series variable (in this case the stock price for Microsoft) over several years of calendars. The site gives R code developed by Paul Bleicher, MD PhD, Chief Medical Officer at Humedica for producing these plots.

A Normal Sidewalk?

I've seen this pattern in many sidewalks. A crack forms at the seam of two pieces of concrete. Over time and use the crack crumbles away portions of the sidewalk in a bell-shaped pattern. What process or differential equation might define the resulting bell-shaped pattern of wear?

The Density of Space Trash

Here is an image showing the density of space debris in low earth orbit. Notice that this density has a very long, and likely heavy, tail that is not shown. Geo-synchronous satellites orbit at 36,000km well off the upper range of this graph (2,000km). There would be a large bump in the density at 36,000km. From The Washington Post.

A Pearl: a Balanced Median Necklace

The September issue of The College Mathematics Journal has this balance point view of the median by Mark Lynch of Millsaps College.