Stats Made Easy

Practical Tools for Effective Experimentation

Thursday, July 19, 2007

Blowing up film takes on a whole new meaning (Part 2 – Statistical analysis)

The results of my mixture design on Alka Seltzer rockets are shown in the graph, which reveals that the flight time in centiseconds (hundredths) lengthened as the proportion of air-to-water increased (p<0.01 for linear mixture model with no significant lack of fit). The predictive equation in terms of real components (fraction of actual space within the film canister) is:

Flight time (seconds) = 1.24Water+1.95Air

For example, a container filled half way with water before dropping in the Alka Seltzer can be expected to propel the lid for 1.59 seconds (159 centiseconds) of flight time (= 1.24x0.5 + 1.95x0.5).

Give this a try and tell me how close you come to this outcome. I guarantee that you will flip your lid. However, be careful -- you'd best wear goggles. I can imagine my mother catching wind of me doing something like this and yelling "that thing will poke your eye out!"


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