1. PERCENT ERROR-MEASURES ACCURACY

2. RECORDED VALUE- The value that was measured ACCEPTED VALUE- The true value. PERCENT ERROR- used to determined how close the recorded value is to the accepted value.

3. PERCENT ERROR FORMULA: ACCEPTED VALUE – RECORDED VALUE X100 ACCEPTED VALUE A shopper measures a 5 pound bag of onions and finds that its 5.2 pounds. What is their percent error?

4. % Error = / 5.0 lbs – 5.2 lbs/ x 100 5.0 lbs % error = /-0.2 lbs/ x100 5 lbs % error = 0.04 x100 = 4%

5. PERCENT DEVIATION- HOW MUCH A MEASURED VALUE IS OFF FROM THE AVERAGE(no accepted value). Mean- average value Absolute deviation- the absolute difference between the mean and the recorded value.

6. % DEVIATION AVERAGE ABSOLUTE DEVIATION X100 MEAN %D = (D a /M )x100

7. STEP 1: Take several readings and find the average. ex: You measure a length of a wooden block and get four measurements. Find your % deviation. 8.9cm + 9.1cm+ 9.0cm + 8.8cm= 35.8cm Mean = 35.8/4 = 8.95

8. STEP 2: FIND ABSOLUTE DEVIATION FOR EACH VALUE / 8.9-8.95/ =.05cm / 9.1-8.95/ =.15cm /9.0 – 8.95/=.05cm / 8.8-8.95/ =.15cm

9. STEP 3: FIND AVERAGE ABSOLUTE DEVIATION.05 +.15 +.05 +.15 =.40cm.40cm =.1cm 4

10. STEP 4: USE FORMULA % DEVIATION= AVERAGE ABSOLUTE DEVIATION X100 MEAN % deviation= 0.1cm x100 = 1.1% 8.95cm What does it all mean?