Accuracy vs. Precision Flashcards
1
Q
Accuracy vs Precision
A
- Are NOT interchangeable
2
Q
Accuracy
A
How close an estimate is to truth (or the true parameter).
3
Q
Precision
A
How repeatable an estimate is. How close our individual estimates are to each other if we make multiple estimates.
4
Q
Target metaphor
A
Accuracy - how close to the target center you are getting
Precision - how close to each other my individual shots are
Accurate AND precise: almost all in the bullseye
Accurate but NOT precise: all shots within the circle, but spread out
Inaccurate and Imprecise: missing the target and spread out
Inaccurate but precise: missing the target, but all shots very close together
5
Q
How does this relate to statistical procedures?
A
Most statistical procedures are designed to be both accurate & precise.
- Most estimators are unbiased
- There’s a trade off between accuracy & precision
- – Estimators that are unbiased often have lower precision than biased ones
- Sometimes we choose to use an estimator that has lower accuracy because it has much high precision
- –Particularly when bias is relatively small
