Time capsule: How to win the ice pool

Time capsule: How to win the ice pool

Note: This Alaska Science Forum "time capsule" article was originally published on May 1, 1976. While employed at the University of Alaska Fairbanks Geophysical Institute, John M. Miller was the Alaska Synthetic Aperture Radar Facility's technical director, and T. Neil Davis, professor of geophysics, founded the Alaska Science Forum 50 years ago. This time capsule is typical of the early columns, which were always tied to newsworthy events and often lighthearted, if not gently self-deprecating.

The Mather Library in UAF's Akasofu Building houses many original supporting materials of this long-running column. At a time when one can use any number of online tools to help you select a date and time to win the next Nenana Ice Classic, the longtime betting game on when the Tanana River will break up, paging through hand-drawn graphs and typewritten drafts is true time travel.

One sure way to win the Nenana Ice Classic is to invest $100,800 to buy 50,400 tickets, one on each minute from about April 18 to May 22. Someone else probably will win, too, so you will probably lose money.

If you believe in statistics at all (and who does?), you can use the diagram below to estimate the probability of having a winning ticket. This probability map is compiled on the basis of the actual breakup times from 1917 to 1975; the hour and day of each is shown on the map.

From these times, a bell-shaped curve was calculated to show the probability of breakup on any specified date. Calculation of the probability of breakups during a particular hour was accomplished by manually smoothing the data, since it appeared that the actual breakups did not, in the parlance of statisticians, follow a normal distribution.

Although a breakup has never occurred during the noon hour of May 6, the probability map says this is the best guess. In principle, such a ticket has 9.6 chances in 100,000 of winning. A ticket falling on the contour line labeled "1" has one chance in 100,000 of winning; one on the "0.1" line has only a chance in a million.

If you choose to ignore the probability contours, which is not a bad idea, you can still glean information from the numbers showing times of actual breakups.

One technique for picking a winning ticket combines both mathematics and skill. Hang the probability map on the wall then throw a dart at it aiming for the top of the "probability hill." If you miss altogether, try another method.

Since the late 1970s, the University of Alaska Fairbanks' Geophysical Institute has provided the Alaska Science Forum column free in cooperation with the UAF research community.