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What a Time Standard Means

Four short lessons on the letters next to a child’s time: a base plus fixed steps, the straight line hidden in the table, why a letter is not a percentile, and why a best time is the luckiest swim of several.

Spark & Whetstone · sparkwhetstone.org/learn/what-a-time-standard-means · CC BY-NC-SA 4.0. Answers are at the end, so you can try each question first.

Lesson 1. A base plus steps

Motivational time standards give six letters, B to AAAA. For 10 & under girls in the 50 freestyle, short-course yards, the 2024–2028 table reads 39.79, 35.99, 32.09, 30.89, 29.59 and 28.29 seconds.

Those numbers are not picked one by one. Each letter sits a fixed number of steps above one base time: B ten steps out, BB seven, A four, AA three, AAA two, AAAA one. The gaps between letters look uneven only because the step counts are.

Question. The B cut is ten steps from the base and the AAAA cut is one. If one step is about 1.28 seconds, roughly how far apart are the B and AAAA cuts?

  1. About 3.9 seconds
  2. About 12.8 seconds
  3. About 11.5 seconds

Say it back. In your own words: how is a time-standard table put together?

Lesson 2. The hidden line

Plot each cut against its number of steps and the six points fall on a straight line. Follow the line back to zero steps and it lands on 27.03 seconds: the base the table is built from, printed nowhere on it.

Each step is about 4.7% of that base. That is why the same idea works for every age and event: a different base, the same recipe. The Cut Card on this site finds the line for any table you type in.

Question. Another table sits on the same kind of line. Its AAAA cut (one step out) is 31.29 and its AA cut (three steps out) is 34.09. Where is its base?

  1. About 29.89 seconds
  2. About 31.29 seconds
  3. About 28.49 seconds

Say it back. In your own words: what is the base, and why is it not printed on the table?

Lesson 3. Percent, not percentile

Club websites use “the B percentage” for different things: a time as a share of a fast time, a claim like “top 30%”, or a time a fixed percent slower than a base. Only the last is how this table is built — the B cut is about 47% slower than the base.

None of the letters says what share of children swim that fast. A percentile would need a count of swimmers, and even then it would count only the swimmers who have a recorded time. The children who never entered a meet are not in that number.

Question. A club page says a B time means “the top 30%”. What is a B cut actually built from?

  1. The fastest 30% of all swimmers last year
  2. A base time plus a fixed number of steps
  3. An age-graded score

Say it back. In your own words: what is the difference between a percent and a percentile here?

Lesson 4. A best time is a minimum

A swimmer’s times scatter a little from race to race. A “best time” is the fastest of several, so it is the luckiest one. For a swimmer who averages 37.2 seconds with a typical spread of 0.45, the best of three is about 0.38 seconds quicker than the average, and the best of ten about 0.69 quicker.

So the next swim is usually a little slower than the best, and a big drop is often followed by a smaller one. That is not a slump — it is what picking the best of many does. Compare a swim with that swimmer’s own usual times, not only with the best.

Question. A swimmer’s best is 37.20, the quickest of five meets. At the next meet she swims 37.55. What is the most likely reading?

  1. She has got slower and something is wrong
  2. A swim a little slower than a best is what usually happens
  3. She has peaked, and a slower swim after a best means her times will now fall away

Say it back. In your own words: why might a child swim slower than their best and still have swum well?

At the table: Find the base

Players: One or two, a grown-up with a swimmer of 10 or older. You'll need: Graph paper, a ruler, a pencil, the printed time-standard table for your swimmer.

  1. Draw an across axis for steps (0 to 10) and an up axis for seconds.
  2. Plot the six cuts at 10, 7, 4, 3, 2 and 1 steps.
  3. Lay a ruler along the points and draw the line back to zero steps. Read off the base.
  4. Check it in the Cut Card, and look at your swimmer’s own last three times on the same paper.

Seat sheets and a run-through: sparkwhetstone.org/cut-card

Answers

  1. About 11.5 seconds — Nine steps of 1.28 seconds is about 11.5 seconds, which is the gap between 39.79 and 28.29.
  2. About 29.89 seconds — (34.09 − 31.29) ÷ 2 = 1.40 seconds a step, and 31.29 − 1.40 = 29.89, the base.
  3. A base time plus a fixed number of steps — The table is a base plus steps. It counts no swimmers, so it cannot say what share of them are faster or slower.
  4. A swim a little slower than a best is what usually happens — A best is the luckiest of several swims, so the next one usually lands nearer her usual time. 0.35 s slower than a best of five is ordinary, not a slump.