Accuracy and Precision

1. This should be review ;) Accuracy and Precision Graphing and Sig-figs

2. Accuracy = how close to the accepted value your measurement is Precision = Reproducibility, your measurement closely matches your other measurements

3. Accurate AND Precise

4. The actual amount is 2.58 mL.Sally, Billy, Stanley, and Petunia each tried to measure the amount and came up with the following results… The most accurate was: Stanley! The most precise was: Sally!

5. You can only measure as precise as the instrument • For example; many home scales only measure to the nearest pound or half pounds but your weight can be measured in grams or milligrams. • The more precise the instrument is the more precisely you can measure something. • So where do we stop? What's the last number to be recorded?

6. What’s the last number we can record • First we decide we know and what we are estimating • If measurement falls between two lines than were estimating the last number

7. If you can measure something to the 10th place you will record the measurement to 100th place • 2.5 cm = 2.50 or 2.51 or 2.53 • Discuss and write how these three measurements are both precise and accurate

8. Let’s measure • We will be measuring three things • We will work in teams and each member will record their data from each instrument • Let’s review how to properly handle, calibrate and use the instruments. • Discuss and write down in full sentences if your data was precise and/or accurate