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James Marsden Hurst 1924—2005 Biography and works
Chapter 2.2 — Timing Is the Key

Hurst's five principles: the cyclic model

Hurst's five cyclic principles explained: summation, commonality, variation, nominality, and proportionality, with examples and limits.

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In one sentence — In J. M. Hurst's model, price combines several cyclic components; five principles explain how they are added, compared, and classified.

The principles are summation, commonality, variation, nominality, and proportionality. Hurst presents them in Chapter 2 of his 1970 book as elements VI–X of the price-motion model. They are assumptions of his historical method, not proven universal laws or standalone trading signals.

The five principles of the cyclic model Elements VI–X presented by J. M. Hurst in Chapter 2 of the 1970 book. Five linked propositions: they describe how the model combines, compares and classifies cycles. HURST 1970 · CH. 2 The five principles of the cyclic model Elements VI–X presented by J. M. Hurst in Chapter 2 of the 1970 book CYCLEPEDIA DIAGRAM — EMICICLO 01 Summation Components + trend → observed shape 02 Commonality A shared family across securities 03 Variation Duration and magnitude fluctuate 04 Nominality Nominal duration is a reference 05 Proportionality In the model: longer duration → greater nominal magnitude Five linked propositions: they describe how the model combines, compares and classifies cycles.
The complete map. Each of the five points opens a definition and a limitation; the essential meaning remains visible without interaction.
Select the highlighted points to explore the detail

1. Summation: what you see is the result

The observed cyclic component would not be a single wave. In the model it is the point-by-point sum of several non-ideal periodic-cyclic components and the trend. Each component differs in magnitude, duration, and phase: the size of its movement, the time required to complete it, and its time position relative to the others.

The lab uses two waves and a straight line. Changing the magnitude of one wave changes the final shape: smaller movements may reinforce each other, cancel out, or become obscured by a longer component.

The summation principle Two waves and a straight line, summed point by point — cf. Figs. III-2 and III-3 in the book. The observed shape depends on what is being summed at each instant. HURST 1970 · CH. 2 The summation principle Two waves and a straight line, summed point by point — cf. Figs. III-2 and III-3 in the book CYCLEPEDIA DIAGRAM — EMICICLO THE INGREDIENTS wave A wave C line B THE SUM A + B + C LONG WAVE 26 wk · magnitude 12 SHORT WAVE 6.5 wk · magnitude 3.5 TREND rising line The observed shape depends on what is being summed at each instant.
A synthetic model inspired by Figures III-2 and III-3: A + B + C produces the lower curve. Wave alignment describes the sum; by itself, it does not generate a signal.
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2. Commonality: an assumption across securities

Hurst proposes that cyclicality is common across securities: components with similar durations, approximately synchronised turns, and comparable relative magnitudes. In the book, he compares Standard Packaging with the DJIA to demonstrate this similarity in the sample studied.

The decisive word is proposes. Commonality belongs to the 1970 model; it does not justify assuming that every instrument, market, or period repeats the same behaviour. A measurement taken from an index should be checked against the security's own data before it is transferred.

3. Variation: actual measurements move

Duration and magnitude do not remain fixed. Under the variation principle, they may change slowly over time, differ across securities, and produce imperfect synchronisation. A component may also become difficult to see when another one dominates the chart.

The practical consequence is straightforward: a recent estimate is a working interval, not a countdown. It must be updated with new observations and should not be forced to make the chart fit the theory.

4. Nominality: the name is not the measurement

The durations in Table II-1 name cyclic families. “26 weeks” is therefore a nominal reference: in the book's 1965–1969 DJIA sample, Hurst measures that component as 21.428 ± 3.5 weeks.

The nominal cycle ladder allows variable measurements to be compared with a common structure. It does not fix the date of the next low, and a measurement is not wrong merely because it differs from its label.

5. Proportionality: duration and magnitude in the model

Hurst associates longer-duration components with a greater nominal magnitude. This relationship helps explain why a long component may dominate many shorter oscillations; it does not mean that every longer cycle will always produce a larger observed movement.

Variation and the overlap of components can hide the relationship in a particular segment. Proportionality should be treated as an internal relationship of the model and checked against the sample being analysed.

How to use them without forcing the chart

When a cyclic hypothesis fails to fit, the five principles suggest five checks: which components are being summed; whether the comparison across instruments holds; how much duration and magnitude are varying; which nominal label is plausible; and which component may be dominant. If the answer requires repeatedly moving lows just to preserve the hypothesis, the hypothesis should be reconsidered.

The 1970 book stops at these five principles. The later Cycles Course tradition reorganises them with three additional principles; the distinction is documented in the eight principles of the cyclic model.

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