1) Pictures are Prophesy
Draw what you’re looking for and then find it. The picture is a prophesy of the promise you made yourself.
2) The Complement Saves Time
“P(at least)” problems are usually “1 – P(none).” Do the complement and move on.
3) Standardize, Then Think
Convert x → z before reading any table. Standardization clears the fog: new unit, same story.
4) Middle First, Then Tails
If you’re unsure, find the middle area, then add or subtract the tails you need. Fewer sign errors, cleaner logic
5) Annotate the Axis
Write μ and σ on the sketch. Future-you will thank present-you when the numbers start to blur.
6) Percentile Means Position
“86th percentile” = “higher than 86 out of 100.” Translate percentiles into rank language people feel.
7) Don’t Worship 1.96
Cutoffs serve decisions, not rituals. If the cost of a miss is high, move the line.
8) Check Units, Then Compute
Minutes vs hours, points vs percent… units warp answers. Confirm the unit before you chase precision.