2019issue C0934-37
Judging a dominant cycle and a trend filter by sample, lag and the move they keep
A short-sample cycle estimate and a long Fourier window do not run on the same clock. They can sit with a trend filter only when each tool is judged by the data it needs, the lag it adds, and whether the slower move is kept or removed.
- A short-sample cycle estimate can be formed from about one cycle of observations, while Fourier analysis needs a much longer, more stable window and therefore answers later.
- Because market series change, a short lookback can track the current cycle better than a long stationary transform.
- A trend filter decides whether the slow, low-frequency part of pink-noise price is kept as a directional move or dropped so a shorter swing can be scored.
- A predictive filter fades quickly more than two or three bars ahead, so the cycle-plus-filter pairing is a statistical setup rather than a long forecast.
Three tools that do not share a clock
A dominant cycle is a short-sample estimate of the strongest repeating component in recent price data. It is used as a local timing baseline rather than a long-history spectrum. A trend filter is a rule that keeps or removes the slower component of price so a strategy can stay with a directional move or isolate a shorter swing. Fourier analysis is a transform that estimates frequency content from a long, relatively stable sample and therefore adds delay when the series is still changing.
A short-sample spectrum method can estimate a local cycle from about one cycle of observations, whereas a Fourier transform needs a much longer window. Because market series change over time, a short lookback can track the current cycle better than a long stationary transform.
Pink noise and the move the filter may keep
Price series can be treated as pink noise: not fully random, with more energy at lower frequencies, so trends can be read as long-cycle segments rather than a separate process. Sine-wave primitives are used to isolate tradable cycles inside that noise and to give a probabilistic location on the wave. Other shapes can be built from the same primitives.
A market model can drop high-frequency chatter and, when swing trading, can also drop trend information so the remaining cycle component is easier to score. Editorial reading: the trend filter is the switch for that choice, keeping the slower component when the aim is a directional move and removing it when the aim is a shorter swing.
A statistical setup, not a long forecast
A predictive filter applied more than two or three bars ahead degrades quickly, so a cycle-plus-filter model is better framed as a statistical setup than as a long forecast.
Percent wins and profit factor are treated as the two primitive performance measures. Several other ratios can be derived from that pair, while an equity curve is a poor first check. Mean-reversion or short-hold swing rules tend to post a higher win rate but a lower profit factor because trades are not left open long enough to capture a full trend move.
When a simpler filter is the better clock
A more complex black-box filter, including a Fourier-style estimator, needs more data and therefore answers later. A simpler filter is preferred when a usable, low-delay output matters more than extra refinement.
All readings on this track · 26 readings
- 1982Critiquing Fourier, Elliott, and seasonal commodity models
- 1982Evaluating half-hour crossovers with cycle priors and stops
- 1984Building moving-window spectral cycle forecasts
- 1988Fourier cycles versus calendar seasonal regimes
- 1989Constructing analog cycle signatures from price lows
- 1990Curve fits fail the forecast test
- 1991Auditing moving-average length with Fourier spectra
- 1991Closed-form phase for dominant-cycle spectra
- 1993Evaluating windowed spectral forecasts of index turning points
- 1994Window length for moving-window spectral forecasts
- 1994Constructing WAMI power and phase spectra
- 1994Fourier-tuned momentum filter design
- 1994Aliasing, leakage, and dominant-cycle reads from sampled prices
- 1995Constructing indicator lookbacks from Fourier spectra
- 1996Constructing phase from a dominant-cycle sine and cosine pair
- 1999Sinusoidal pseudo-securities for indicator evaluation
- 2000Constructing dominant cycle length from Hilbert phase
- 2000Constructing adaptive channel breakouts from a measured cycle period
- 2005Embedding forex prices into a singular-spectrum forecast basis
- 2005Constructing recurrent forecasts from grouped spectral components
- 2007Constructing a dominant cycle from transformed Fourier spectra
- 2010Why cycle indicators fail when parameters shift
- 2019Constructing futures momentum as open-interest-scaled rate of change
- 2019Judging a dominant cycle and a trend filter by sample, lag and the move they keep
- 2020Constructing futures turnover time and urgency
- 2020Stock power ratio as a growth trend filter