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Math & numbers Ideas & discovery

How to understand probability in everyday life

Judge chance and odds in real life, not just on dice.

A course on probability for everyday judgement. It covers what a probability actually is, how to combine chances, why rare things happen all the time, the traps that catch almost everyone, and how to use base rates and expected value to decide better.

iPhone App Store Get Cadence free

Open Cadence on the App Store, type the sentence when it asks what you want to learn, and answer a few setup questions. Free to start. Android testers can request early access.

Start with three things you can do today

Type this when Cadence asks what you want to learn

I want to understand probability well enough to judge odds, risk and chance in real life. Use everyday situations rather than dice and cards, and show me the common traps people fall into.

Change any word so it fits your situation. The course is built from what you type and a few setup questions.

Start today

Three things you can do before the course exists.

Useful on their own. The course is for when you want the whole skill, not just the first move.

  1. Turn every percentage into people

    Thirty percent chance of rain means three days in ten like this one. Natural frequencies are far easier to reason with than percentages.

  2. Ask how many chances there were

    A one in a million coincidence with a million chances is expected. Rare per attempt is not rare overall.

  3. Remember the coin has no memory

    After five heads, tails is not due. Each flip is the first flip. Most gambling mistakes are this one in disguise.

Best for
Math & numbers
Prerequisites
None. Bring the situation you have.
Course length
7 to 30 lessons, sized to your goal
Lesson pace
About 10 minutes a day
Format
Read it, or play the audio
Access
Available on the App Store, with early features and Android testing access

Before the course is built

Setup asks about your situation first.

Lesson 1 opens on the moment you describe, and the examples use your role. For this request, expect questions like these.

  1. Where does chance come up for you: health decisions, money, work forecasts, or just curiosity?
  2. How comfortable are you with fractions and percentages?
  3. Is there a specific kind of decision you want to think through better?

Right for now

If any of this sounds familiar, start here.

Odds mean nothing to you

A thirty percent chance of rain and no idea what to do with it.

You are surprised by coincidences

It could not be chance, could it?

You want to decide better under uncertainty

Bets, insurance, medical tests, plans.

Course arc

Where the course goes, in order.

Cadence writes the lessons for you, so the exact path follows your answers. This is the ground a course built from this sentence covers.

01 / 06

What a probability is

Percent, odds and frequency, translated.

Combining chances

Independence, and the common error that breaks everything.

Rare things happen

Why coincidences are expected, and lotteries are won.

Base rates

The test result, the rare disease, and the maths people get wrong.

Expected value

A way to compare choices with uncertain outcomes.

The traps

Gambler's fallacy, hot hands, and the stories we tell about luck.

What changes

What you will be able to do, and what you will stop believing.

You will be able to

Know what probability means

Frequencies, beliefs, and why both matter.

Combine chances

And, or, and the mistake of multiplying what is not independent.

Use base rates

How prevalence and test accuracy affect the meaning of a positive result.

Decide with expected value

Weighing outcomes by their chances, and when not to.

Ideas this course corrects

After five heads, tails is due

For independent flips of a fair coin, earlier results do not change the next flip's one-half probability.

A one in a million event is impossible

Across many opportunities, a rare event becomes more plausible. The chance still depends on the number and relationship of those opportunities.

Course questions

What to know before you start.

How to understand probability in everyday life: what can I do today?

Turn every percentage into people. Thirty percent chance of rain means three days in ten like this one. Natural frequencies are far easier to reason with than percentages. Ask how many chances there were. A one in a million coincidence with a million chances is expected. Rare per attempt is not rare overall. Remember the coin has no memory. After five heads, tails is not due. Each flip is the first flip. Most gambling mistakes are this one in disguise.

Is this a fixed course?

No. Cadence builds the course when you type the sentence and answer a few setup questions, so the lessons follow your situation. This page describes what a course built from this request covers. You see the whole path before Lesson 1.

Who is this course for?

A course on probability for everyday judgement. It covers what a probability actually is, how to combine chances, why rare things happen all the time, the traps that catch almost everyone, and how to use base rates and expected value to decide better. It sits under Math & numbers in the Ideas & discovery part of the library.

Do I need any prior experience?

No. Setup asks what you already know and where you want to use it, and the course starts from there. Bring a real situation if you have one; the examples are built around it.

How long does it take?

Courses run 7 to 30 lessons of about 10 minutes, sized to what you asked for. One lesson a day is the intended pace, and you can go faster. Lessons can be read or played as audio.

Does this course award a certificate or degree?

No. Cadence is for practical self-learning and does not award accredited degrees or professional certification.

Start today

Type it, answer a few questions, open Lesson 1.

The sentence to type

I want to understand probability well enough to judge odds, risk and chance in real life. Use everyday situations rather than dice and cards, and show me the common traps people fall into.
iPhone App Store Get Cadence free

Open Cadence on the App Store, type the sentence when it asks what you want to learn, and answer a few setup questions. Free to start. Android testers can request early access.

Android early access

Join Cadence on Android.

Tell us your goal and Google Play email. We will send your tester invite when it is ready.

Use the email on the Google account you use with Google Play. We only use it for your tester invite and Android testing updates.