MeritKeep

Report a messy number to someone who will act on it

You are given, or can find, a distribution that is genuinely awkward — skewed, small, or with a long tail. Salaries, delivery times, response times and support ticket ages all work. Write the one-paragraph summary a decision-maker would receive. The difficulty is not the arithmetic; it is choosing what to leave out without making the figure mean something it does not.

Part of the Statistics & Data Literacy course~75 minutesEvidence: a write-upWe mark it against a checklist you can read first
01 · What counts as done

What you have to hand in

  • One paragraph, aimed at a numerate non-specialist.
  • The summary statistic chosen, with a reason drawn from the shape of the data.
  • The alternative statistic named, and what it would have implied.
  • A spread figure in the same units, chosen for what a reader would act on.
  • A visible denominator and rounding the sample can bear.
  • A line saying what the figure excludes.
02 · How it will be marked

The checklist, published before you start

We score your work against each line below, and every score has to quote the part of your work it is based on. You read all of it first, so you can argue with any score on the specifics.
  • The summary statistic fits the data30% of the grade

    The choice of mean, median or percentile is justified by the shape described.

    1. AbsentA mean reported for an obviously skewed distribution, unremarked.
    2. DevelopingA defensible statistic chosen, with no reason given.
    3. Competent— this is the pass markThe right statistic with a stated reason drawn from the shape.
    4. StrongRight, reasoned, and the discarded alternative named with what it would have implied.
  • Variation is reported, not just the centre25% of the grade

    The reader can tell how much the quantity varies, not only where it sits.

    1. AbsentA single number with no indication of spread.
    2. DevelopingSpread mentioned qualitatively but not quantified.
    3. Competent— this is the pass markA concrete spread figure in the same units as the centre.
    4. StrongSpread given as the figure a reader would act on, such as a high percentile.
  • No more precision than the data supports25% of the grade

    Figures are rounded to what the sample can bear, and denominators are present.

    1. AbsentSeveral decimal places on a small sample, or a percentage with no denominator.
    2. DevelopingDenominator present, precision overstated, or vice versa.
    3. Competent— this is the pass markSensible rounding and a visible denominator.
    4. StrongBoth, plus a stated note on what the figure excludes.
  • A non-specialist can act on it20% of the grade

    The summary is written for the decision-maker, not for another analyst.

    1. AbsentJargon-dense, or requires the reader to do the interpretation.
    2. DevelopingUnderstandable after effort.
    3. Competent— this is the pass markClear to a numerate non-specialist.
    4. StrongThe decision it supports is obvious from the summary alone.
03 · What this proves

The skills a pass would prove

Pass, and these skills count as proven, with this piece of work attached as the evidence.

This brief is part of the Statistics & Data Literacy course

Starting it starts the course: every skill above, in the order they depend on each other, with this brief at the end as the thing you hand in — marked against the checklist you have just read and nothing else.

About three minutes to set up: what you want to do with Statistics & Data Literacy, where you are starting from, and how many hours a week you actually have. The subject we already have from this page.Start the Statistics & Data Literacy course
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