Volatility tools

Volatility is the variability of a price series under a specified measure. Two charts can have the same upward net change but very different journeys: one rises quietly and another swings sharply up and down before ending at the same level. A volatility tool summarises parts of that journey. It does not choose buy or sell, and it cannot set a maximum possible future loss.

This lesson compares average true range, which summarises ranges and certain gaps, with Bollinger Bands, which place a dispersion measure around an average. Keep timeframe and units visible. A daily range in yen cannot be compared directly with an hourly range in dollars; the number is meaningful only alongside its definition.

An ordinary bar range is its high minus its low. That can miss a jump from the previous close. True range compares three non-negative distances: current high minus current low, the absolute distance from current high to previous close, and the absolute distance from current low to previous close. The largest is selected. Absolute distance means ignore the sign when measuring how far apart two prices are.

If you used only the 0.40-yen high–low range, you would miss much of the move from the earlier close. This matters around weekend openings, session differences and any instrument with discontinuous quotes. True range still summarises observed prices; it does not guarantee an executable fill existed at every intermediate price.

Average true range, or ATR, smooths successive true ranges. J. Welles Wilder developed ATR and presented it in his 1978 work on technical trading systems. A common lookback is 14 periods. Wilder-style smoothing uses the previous ATR multiplied by n − 1, adds the latest true range, then divides by n. Different platforms can use different averaging choices, so check their documentation.

ATR has no positive or negative direction. A large fall and a large rise can both increase it. A daily EUR/USD ATR of 0.0060 corresponds to 60 conventional pips, whereas USD/JPY uses a conventional 0.01 pip step. Always label the quote units before calling a number small or large.

A daily ATR and a five-minute ATR summarise different observations. Two pairs with different quote magnitudes can have different raw ATR numbers even if their percentage variability is similar. For a descriptive cross-market comparison, ATR divided by a suitable price and multiplied by 100 produces an approximate percentage measure. Use comparable timeframes and price conventions; this still is not a prediction.

ATR often increases after the price movement has already occurred. Waiting for a larger number does not guarantee calmer execution, and a low number does not prove safety. A calm sample can be followed by a sharp announcement-driven move.

A planned stop distance is a price distance from an intended entry to an invalidation level. Some learners compare this distance with recent ATR as a descriptive check. An ATR multiple is not automatically a good stop: the reason the idea fails, trading costs, instrument specification and execution still matter. A stop can be wider yet expose less money if the position is smaller.

John Bollinger developed Bollinger Bands in the 1980s. A conventional setup places a 20-period simple moving average in the middle and outer lines two standard deviations above and below it. These are defaults, not instructions that every market or timeframe should use them. The middle line describes a recent centre; standard deviation describes dispersion around a mean under a calculation convention.

In an invented EUR/USD example, a mean of 1.1000 and standard deviation of 0.0020 with k = 2 give upper 1.1040 and lower 1.0960. The total band width is 0.0080, or 80 conventional pips. This arithmetic uses given inputs; calculating the standard deviation itself requires the whole window and its convention.

Bands widen when dispersion in the chosen sample grows and narrow when it shrinks. A squeeze is a description of unusually narrow bands under a comparison rule. It does not reveal the direction of a later breakout or ensure one arrives immediately. Define what “narrow” means relative to an earlier period rather than choosing an attractive example after the event.

A price touching the upper band is relatively high under the current calculation, not an automatic sell. A lower-band touch is not an automatic buy. During a trend, successive closes can stay near an outer band. An older extreme leaving the window can also change the bands even if the latest candle is uneventful.

ATR and Bollinger width are related descriptions derived from market prices, though their formulas differ. Adding both can help answer different questions, but agreement does not mean two independent witnesses have confirmed a trade. Averages, RSI and band calculations can all be responding to the same input history.

On one demo feed, record the pair, completed-bar time, timeframe, ATR lookback, smoothing, quote units, band lookback, multiplier and price input. Record the actual numbers before interpreting them. Note scheduled events separately. If you compare a quiet session with a busy one, use the same settings and define the sample rather than discarding inconvenient observations.

Next, translate an observed distance into pips and an ideal cash amount. Keep the quote distance, position units, conversion and fees as separate entries. This helps expose a common mistake: treating a volatility reading as account risk even though no position size has been specified.

To finish the exercise, explain why ATR cannot choose direction and why a band touch cannot supply its own probability. If you can calculate the value but cannot state the unknowns, revisit the interpretation sections.