## Appendix C: Construction of Log Scaled Charts

There are a number of ways to take the log of a number. The two most common are log base 10 and log base e, or natural log, (ln). The natural log is preferred for log scaled charts.

To construct a log scaled chart you must proceed as follows:

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* *Decide on a box size. This is done by either deciding on a logged value, or, better still, a percentage change in price, because this is easy to understand and apply.
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* *The box increment is therefore (1 + % change). For example, if you have chosen a box size of 1%, the box increment is 1.01. In other words, the next box value is 1.01 times the previous box.
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* *Take the ln of the box increment. The ln of 1.01 is 0.00995.
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* *Take the ln of the starting price ...