Proofset Academy · Lesson 4.3

Variance in figures

Even with a good win rate, losing streaks happen. It is not a sign that something is wrong: it is chance, normal and predictable. This lesson gives the figures, so that streaks no longer come as a surprise, and shows how many bets are needed before a method can be judged.

Know that a good win rate does not prevent losing streaks.

Read the table of losing streaks over 100 bets.

Calculate the risk of a streak yourself, according to your win rate and number of bets.

See a run of 100 simulated bets, and its longest losing streak.

Understand the normal range of the number of wins.

Know why a method is not judged on a few dozen bets.

Part 1

Losing streaks over 100 bets

Probability of suffering at least one streak of consecutive losses over 100 independent bets, according to the win rate. The darker the cell, the more likely the streak.

Win rate	4 losses in a row	5 losses in a row	6 losses in a row	8 losses in a row

How to read it: at a 60 % win rate, there is almost a one-in-two chance (45,9 %) of suffering at least 5 losses in a row over 100 bets. Even at 75 %, a streak of 4 losses happens one time in four. It is not a sign that the method no longer works: it is normal chance.

Part 3 · Animation

A hundred bets, simulated

Here are 100 bets simulated at the rate chosen above. Green: won. Orange: lost. The longest losing streak is circled. Run it again several times.

Part 5

Judging a method: it takes hundreds of bets

The range shows it: over 30 bets, a true win rate of 60 % can produce, without anything having changed, an observed result of about 42 % to 78 %. No conclusion is possible. Over 500 bets, the range falls to about 56 % to 64 %.

At Proofset too

The Academy's measurements always state their number of matches and their margin of error. The “ELO favourite at 65 % or more and 100 % dominant” group, for example: 85,8 % wins over 141 matches, but the gap to the market has a margin of error of ± 5,6 points (lesson 2.5).

For yourself

Draw no conclusion from fewer than a few hundred bets. A good or bad run of 20 bets says nothing about the way you bet.

Key points

Losing streaks are normal. At 60 %, a streak of 5 happens almost one time in two over 100 bets.
They are prepared for in advance, by choosing a unit small enough to get through them (lesson 4.1).
A streak justifies neither raising stakes nor changing method in a panic (lesson 4.4).

Part 6

Test yourself

7 questions. You need 6 correct answers to pass the lesson.

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