Understanding Deviation
STEP 1 · LEARN
Deviation tells us how far an observed result is above or below what we expected. It's the gap between what should happen, on average, and what actually happened in a given sample.
A small deviation is normal — results always wobble around the expected value. A strategy pays attention to deviation because a large, sustained deviation can signal a condition worth watching, not because any single deviation predicts what happens next.
STEP 2 · SEE
DEVIATION: −30%
STEP 3 · UNDERSTAND THE FORMULA
((Actual − Expected) / Expected) × 100
ACTUALWhat was actually observed in the sample.
EXPECTEDWhat the baseline probability predicts.
× 100Converts the ratio into a percentage.
STEP 4 · PRACTICE
A digit was expected to appear 10 times but appeared 12 times. What is the deviation?
A+2%
B+20%
C−20%
D+120%
CORRECT ✓
12 is 2 above the expected 10. That represents a +20% deviation.
NOT QUITE
Start by finding how far the actual value is from the expected value, then divide by the expected value.