📐 The Rice Purity Test Formula — Explained

A deep dive into the math behind the Rice Purity Test. The formula is simple — but understanding it properly means understanding what the score does and doesn't tell you.

The Formula

Score = 100 − N

Purity Score = 100 − N

Variables

  • 100 — Total number of questions (fixed)
  • N — Number of questions answered "yes" (0 to 100)
  • Score — Result; always an integer from 0 to 100

Constraints

  • N must be ≥ 0 (can't check negative items)
  • N must be ≤ 100 (can't exceed total questions)
  • Score is always a whole number
  • No fractions, no decimals, no rounding needed
Design Rationale

Why This Formula?

The formula was chosen for its simplicity and interpretability. Starting at 100 and counting down creates an intuitive scale: you begin pure and lose points for each experience. This matches the "purity" framing of the test.

Alternative designs (like starting at 0 and adding points, or weighting items differently) would make the score harder to interpret quickly. A score of 73 is instantly meaningful — you've had 27 of the 100 experiences — whereas a weighted score would require more explanation.

The equal weighting of all 100 questions is also intentional. Treating all experiences equally avoids the political and moral minefield of deciding which experiences are "worse" than others. The test is explicitly non-judgmental in its design.

Worked Examples

Formula in Action

Checked (N)CalculationScoreLabel
0100 − 0100Completely Innocent
5100 − 595Very Pure
15100 − 1585Relatively Pure
30100 − 3070Experienced
50100 − 5050Experienced
70100 − 7030Very Experienced
90100 − 9010Maximally Impure
100100 − 1000Maximally Impure
Limitations

What the Formula Doesn't Capture

Understanding the formula also means understanding its limits:

  • No context: Checking "used marijuana" tells you nothing about whether it was once or thousands of times, whether it was legal, or whether it was a positive or negative experience.
  • No recency: Something you did 20 years ago and something you did yesterday count the same.
  • No circumstances: Consensual vs. non-consensual, safe vs. risky, legal vs. illegal — the formula doesn't distinguish.
  • No personality: Two people with the same score can be completely different people with completely different values.

This is why the test is a social curiosity tool, not a character assessment. The formula is simple by design, not by accident.


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