Part II
There is another dimension to the choice of box size. This hinges on the consideration that it was much easier to maintain longer-term hand drawn charts directly from the basic chart, rather than from the original data. For this reason, we try to keep the box sizes such that each larger box is twice the smaller one. This was easy on Wall Street, where the smallest quotes were in eighths, so the chart sizes were eighths, quarters, halves, dollars and so on. However, in Australia, the lowest share price is one tenth of a cent. This drives the starting point, and the sequence of box sizes would be 0.1c, 0.2c, 0.4c, 0.8c, 1.6c, 3.2c and so on, if it were not for the need to take another consideration into account.
This is a phenomenon of support and resistance levels â that people tend to think and bid/offer prices in round numbers â the so-called âpsychologically importantâ numbers that occur in all markets. Since the primary reason behind filtering the prices in the point and figure method is to detect when the price breaks beyond support and resistance levels, it is highly desirable to use round numbers in choosing box sizes.
Thus, the convention is to use the sequence 0.1c, 0.2c, 0.5c, 1c, 2c, 5c, 10c, 20c, (sometimes 25c), 50c, $1.00, $2.00, $5.00 and so on. It is therefore necessary to have access to the original data when moving from a 0.2c to a 0.5c, or 2c to 5c, or 20c to 50c (and so on) box size.
Fortunately, with use of a computer to draw the charts for us, this is less of a problem than it was a decade ago.
Putting it all together, we can express the guidelines in the following table:
Midpoint of Price Range: 5 10 25 50 100 250 500 1000
Box size: 0.1 0.2 0.5 1 2 5 10 20
The same considerations will drive choice of box size in any market, by starting with the minimum bid and moving up in the sequence as shown above. For example, in the interest rate or currency markets, substitute basis points or decimals of a currency unit for the basic one tenth of a cent above and start with the two percent rule.
The discussion of box size has been lengthy, but, as this is the most difficult aspect of the method for beginners, it needs a solid explanation.
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Warning: MetaStock, SuperCharts and some other charting software do not draw the basic one box reversal point and figure chart correctly. This seems to be because the US market has swung over almost entirely to small box sizes with condensed charts using the three box reversal method. They have overlooked that the one box reversal chart is drawn such that there is always a minimum of two boxes plotted in any one column. The need for this is quite strongly based in the classic books by De Villiers, Wyckoff, Gartley and Wheelan. Indeed, CompuTrac and Telerate charting software in the US use the correct method, as does Insight Trader in Australia.