Tukey's Bulging Rule
for Straightening Data
Bruce Ratner, Ph.D.
"A very effective and simple technique for straightening data is re-expressing the variables, which uses Tukey’s Ladder of Powers and the Bulging Rule. Before presenting the details of the technique, it is worth discussing the importance of straight-line relationships or straight data."
- Ratner, B., Statistical Modeling and Analysis for Database Marketing: Effective Techniques for Mining Big Data, CRC Press, Boca Raton, 2006. The following is an excerpt from Chapter 3, pages 39 -41.
3.5.2 Bulging Rule
The Bulging Rule states the following:
Re-expressing is an important, yet fallible part of EDA detective work. While it will typically result in straightening the data, it might result in a deterioration of information. Here is why: re-expression (going down too far) has the potential to squeeze the data so much that its values become indistinguishable, resulting in a loss of information. Expansion (going up too far) can potentially pull apart the data so much that the new far-apart values lie within an artificial range, resulting in a spurious gain of information. ... An excellent real-case illustration follows (pages 41- 50 in the book).
0. Tukey's Bulging Rule: What to Do When It Fails
1. The Correlation Coefficient: Definition
2. When Data Are Not Straight
3. Data Mining and Its Applications
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