1. Accuracy vs. Precision

2. Accuracy
Accuracy = the extent to which a measured value agrees with a standard value
Accuracy of a device must be checked
Does it read a proper accepted value?
Beware of Parallax – the apparent shift in position when viewed at a different angle.

3. Example: Accuracy
Who is more accurate when measuring a book that has a true length of 17.0 cm?
Susan:
17.0 cm, 16.0 cm, 18.0 cm, 15.0 cm
Amy:
15.5 cm, 15.0 cm, 15.2 cm, 15.3 cm

4. Precision
Precision = the degree of exactness of a measurement that is repeatedly recorded.
Which set is more precise?
18.2 , 18.4 , 18.35
17.9 , 18.3 , 18.85
16.8 , 17.2 , 19.44

5. Example: Precision
Who is more precise when measuring the same cm book?
Susan:
17.0 cm, 16.0 cm, 18.0 cm, 15.0 cm
Amy:
15.5 cm, 15.0 cm, 15.2 cm, 15.3 cm

6. Accuracy vs Precision Groupings Precise, not accurate
Accurate, not precise
Precise and accurate
Groupings

7. Accuracy vs. Precision Less Precise More Precise More Accurate
Less Accurate x

8. Accuracy vs Precision

9. Accuracy vs. Precision High Accuracy High Precision
High Precision Low Accuracy

10. Can you hit the bull's-eye?
Three targets with three arrows each to shoot.
Both accurate and precise
Precise but not accurate
Neither accurate nor precise
How do they compare?
Can you define accuracy vs. precision?

12. Graduated Cylinder – Meniscus and Parallax

13. Why Is There Uncertainty?
Measurements are performed with instruments, and no instrument can read to an infinite number of decimal places
Which of the instruments below has the greatest uncertainty in measurement?

14. Evaluate whether the following are precise, accurate or both.
High Accuracy
High Precision
Low Accuracy
Low Precision
Low Accuracy
High Precision

15. Accuracy vs Precision

16. ACCURACY VS. PRECISION GAME