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MarkerDrift Journal · method, data, sources

Load, read properly.

Method articles for people who monitor athletes: definitions, formulas, worked examples and checked sources. Every number can be reproduced, and the dossier data can be downloaded.

  • 2 articles
  • 8 basics entries
  • 6 coming up
  • a new one every 10 days

Outside his usualHigher than his last 8 MD-3 days. Worth a look, not a verdict.

His norm (last 8 MD-3)One dayOutside the norm

Featured

The latest dossier

A dossier measures a real question on the demo club’s data, with the calculation to download.

48.1%
Dossier · Statistics for the staff · 13 min read

48%: the anatomy of an alert rule that cried wolf

On a simulated season a common rule lit up one day in two. The first fix brought it down to 8%, but for the wrong reason

MarkerDrift team3 November 2026intermediate

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The library

All articles

Filter by type or by topic. A new one every 10 days.

  • Dossier
    Dossier · Statistics for the staff

    48%: the anatomy of an alert rule that cried wolf

    On a simulated season a common rule lit up one day in two. The first fix brought it down to 8%, but for the wrong reason

    13 min read3 November 2026intermediate

  • Basics
    Basics · Statistics for the staff

    The team average is not a norm

    Why a number should be read against the athlete themselves, and what the squad average is really for

    7 min read26 October 2026basic

  • Coming 19 November
    Basics · Clean data and technology

    A data gap is not a rest day

  • Coming 29 November
    Basics · Load and the microcycle

    The microcycle explained: MD-4 to MD+2

  • Coming 9 December
    Guide · Internal load

    Session RPE, done right

  • Coming 19 December
    Basics · Load and the microcycle

    Minutes played are data

  • Coming 29 December
    Guide · Internal load

    Don't add up your wellness questionnaire

  • Coming 8 January
    Guide · Load and the microcycle

    Load monitoring in football: a practical guide

Basics

The definitions, with the formula

The words every article uses. Tap an entry for the formula.

  • z-scoreHow many standard deviations a value sits from the mean of its norm.

    z = (x − mean) ÷ SDsample SD, with n − 1

  • Typical errorHow much a measure moves on its own, across repeated trials of the same person (Hopkins, 2000).

    TE = SD of the differences between two trials ÷ √2

  • Coefficient of variationThe standard deviation as a percentage of the mean: the noise of a measure in one number.

    CV = SD ÷ mean × 100

  • sRPEThe internal load of a session: minutes times perceived exertion (Foster).

    sRPE = duration (min) × RPE (CR-10)in arbitrary units (AU)

  • ACWRThe ratio between recent load and baseline load. It describes how much load is changing; it does not predict anything.

    ACWR = acute (7 days) ÷ chronic (28 days)uncoupled: the chronic load leaves out the acute days

  • EWMAA moving average that gives more weight to recent days.

    λ = 2 ÷ (N + 1)today = λ × load + (1 − λ) × yesterday

  • Monotony and strainHow alike the days of the week are (Foster), and the load weighted by that likeness.

    monotony = mean ÷ SD of the 7 days (rest = 0)strain = weekly load × monotony

  • MD and the microcycleThe football week turns on the match: MD-1 is the day before, MD+1 the day after.

    compare the same MD and the same kind of daynever “Tuesday against Tuesday”

Calendar

Coming up

  • A data gap is not a rest dayBasics · Clean data and technology
  • The microcycle explained: MD-4 to MD+2Basics · Load and the microcycle
  • Session RPE, done rightGuide · Internal load
  • Minutes played are dataBasics · Load and the microcycle
  • Don't add up your wellness questionnaireGuide · Internal load
  • Load monitoring in football: a practical guideGuide · Load and the microcycle

A new article every 10 days: we announce it on the MarkerDrift LinkedIn page and in the RSS feed.

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