1. Accuracy vs Precision

2. Are you accurate?
Accuracy is how close your measurement is to the real value
Subtract your value from the real value to determine how accurate you are (how far off).

3. Are you precise?
Precision is how close your measurements are to each other
How consistent you are
May not be the most accurate
Subtract your highest value from the lowest value to determine how precise you are (how consistent).

4. Check your understanding:
2 students timed the period of a pendulum 3 times each. The period should have been 2.8 sec.
Bob  2.7 s 1.5 s 4.8 s
Elmo  2.4 s 2.5 s 2.4 s
1) Who was most accurate? How do you know?
2) Who was most precise? How do you know?

5. Check your understanding:
2 students timed the period of a pendulum 3 times each. The period should have been 2.8 sec.
Bob  2.7 s 1.5 s 4.8 s
Elmo  2.4 s 2.5 s 2.4 s
1) Who was most accurate? How do you know?
2) Who was most precise? How do you know?
Bob – 2.7s is closest to 2.8s
Elmo – he consistently times around 2.4s