FTB-C000019 / Formula component

Smoothing Constant

A smoothing constant controls how far an exponential state moves toward each new observation.

Also known asalphaEMA tracking rate

Intermediate 12 linked topicsPublished

Definitions

In plain terms

A larger smoothing constant makes an EMA respond faster to new data, while a smaller value makes it change more slowly and remember older observations longer.

Technical

In EMA_t = EMA_(t-1) + alpha(z_t - EMA_(t-1)), alpha is a dimensionless value between zero and one that multiplies the current forecast error.

Scope

This concept describes the recurrence weight; it does not independently specify initialization, warm-up length, missing-data handling, or predictive value.

Examples

  • Alpha 0.10 closes 10 percent of the gap between the prior EMA and the current observation.

Common misconceptions

  • A 10 percent smoothing constant does not mean only the latest ten observations are used.

Concept relationships

Related

Feeds into

Required by

Where this concept is used

Tutorials planned

These catalogued topics use this concept, but their complete build has not shipped yet.

  • D04-F02-A01 Important
  • D04-F02-A02 Important
  • D04-F02-A03 Important
  • D04-F02-A05 Important
  • D04-F02-A06 Important
  • D07-F01-A02 Important
  • D07-F01-A04 Important
  • D07-F01-A05 Prerequisite
  • D07-F01-A06 Prerequisite
  • D07-F01-A08 Important
  • D07-F01-A09 Important
  • D07-F02-A01 Prerequisite

Evidence and governance

  1. Calculating the McClellan Oscillator McClellan Financial Publications · first party methodology

    Supports: preferred label, short definition, technical definition, formula, units

    Limits: Does not prescribe one universal initialization, missing-session, revision-resolution, rounding, or software interface policy.

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Last reviewed
2026-07-26
Next review
2027-07-26
Record status
published
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Fintech engineer building market-data and financial systems, and the author of every article, glossary record, and reference implementation on The Fintech Builder.