felixs.dev / correlation-vs-causation-quiz
[READ-ONLY] Mirror of https://github.com/trueberryless/correlation-vs-causation-quiz. Find out if you know the difference between correlation and causation in this short quiz. correlation-vs-causation-quiz.felixs.dev
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README.md

Correlation vs Causation Quiz #

Netlify Status

An interactive quiz to test your ability to distinguish between correlation and causation.

Features #

  • English and German, with the language remembered in a cookie
  • 10 random questions per attempt (5 causal, 5 correlation)
  • A confidence rating (50-100 %) for every answer, which has to be set before answering
  • Up to 5 attempts per device
  • A statistics page with the global results and a difficulty analysis of every question
  • Results are stored locally and submitted to this repository through a server endpoint

How it works #

  1. A visitor gets 10 random questions, 5 causal and 5 correlation ones, from shared/data/questions.json.
  2. For each question they set their confidence and choose "Causal relationship" or "Just correlation".
  3. After the last question they estimate how many answers were correct.
  4. The result is saved in the browser and sent to POST /api/submit-results. The endpoint appends it to results/<anonymous id>.json in a new branch and opens a pull request.
  5. GET /api/get-stats returns all results that were merged into the results/ folder and GET /api/question-difficulty ranks the questions by their error rate, weighted by the number of attempts.

Development #

Requires Node.js 24 and pnpm.

pnpm install
pnpm dev

Without a GitHub token the quiz works, the statistics are empty and submitting results fails (the quiz tells the visitor that the results were only saved locally).

Environment variables #

Create a .env file to try the submission:

GITHUB_TOKEN=a personal access token with the repo scope
PUBLIC_REPO_OWNER=trueberryless
PUBLIC_REPO_NAME=correlation-vs-causation-quiz

The token is only used on the server. Requests are validated with Zod: one result per request, an anonymous id of 10 to 40 characters (letters, digits, _ and -) and the value ranges of the quiz.

Commands #

Command Description
pnpm check Type check with nuxt typecheck
pnpm lint Lint with oxlint
pnpm format:check Check formatting with oxfmt
pnpm knip Find unused files and dependencies
pnpm test Unit and component tests with Vitest
pnpm test:e2e Build, then run the Playwright end-to-end tests

Project structure #

app/            pages, components and the quiz composable
i18n/locales/   English and German messages
server/api/     the three endpoints
server/utils/   GitHub storage and request validation
shared/         quiz and statistics logic, constants, questions
results/        one JSON file per device (in the GitHub repository)
test/           unit, component and end-to-end tests

License #

Licensed under the MIT license, Copyright © trueberryless.

See LICENSE for more information.