1. Two important points in measurement
Accuracy & Precision
Two important points in measurement

2. Accuracy and Precision At the conclusion of our time together, you should be able to:
Explain the difference between the accuracy and precision
Give examples of accuracy and precision

3. 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.

4. Graduated Cylinder – Meniscus and Parallax

6. 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

7. Murphy's Laws of Science and Technology
Technology is dominated by those who manage what they do not understand.

8. 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

9. Example: Precision
Who is more precise when measuring the same 17.0 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

10. Accuracy vs. Precision High Accuracy High Precision High Precision
Low Accuracy

11. 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. 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?

13. Braille dots are on the keypads of drive-up ATM's?
The Scientific Method begins with Questions about the World Around You. Ever Wonder Why?...
Braille dots are on the keypads of drive-up ATM's? 13

14. Accuracy and Precision Let’s see if you can:
Explain the difference between the accuracy and precision
Give examples of accuracy and precision

15. Exit Quiz: Evaluate whether the following are precise, accurate or both.
High Accuracy
High Precision
Low Accuracy
Low Precision
Low Accuracy
High Precision