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Date Posted: Saturday, February 16, 05:50:59am
Author: Dave Zitzkat
Subject: Using Chi Square
In reply to: Dave Zitzkat 's message, "Statistically Debunking the Space Cadets" on Saturday, February 16, 05:34:35am

The simplest way to look at this is using a Chi Squared Analysis, actual vs expected.

Here are my calculations.

Actual = Actual change in number of students enrolled based upon previous year's figure

Expected = Number of new students predicted by Space Cadet model

Year Actual Expected A - E (A - E)2 (A - E)2/E

2001 35 132.3 -97.3 9467 72

2002 -2 170.1 -172.1 26,618 156

2003 -20 126.9 -146.9 21,580 170

2004 30 129.9 -96.9 9390 74

2005 -29 99.9 -128.9 16,615 166

2006 5 56.7 -51.7 2673 47


The Chi Square value = 761

Degrees of Freedom = 6

Comparing against Right Tail Standard Chi Square values, this is off the charts. For example, a Chi Square value of 22.458 would define a right tail of 0.001. This value is way beyond that, and thus off the charts. This of course means that the expected values are nowhere even close to the actual values.

2007 -14 43.2 -57.2 3272 76

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