1. Error, Accuracy, Deviation, and Precision in Lab data

2. Common misconception:  Any mistake in a lab is considered Error?  NOT TRUE, lab Error does NOT include calculating wrong, measuring wrong, etc…

3. TYPES OF ERRORS: Systematic & Random  Systematic Error u Produces an error that is always the same. Either always high or always low.

4. TYPES OF SYSTEMATIC ERROR  INSTRUMENTAL ERROR u caused by faulty inaccurate equipment, use in labs  PERSONAL ERROR u caused by some peculiarity or bias of the observer—not acceptable in labs, these are “mistakes”  EXTERNAL ERROR u caused by external conditions, use in labs if applicable

5. TYPES OF ERRORS  RANDOM ERROR:  Errors that are due solely to chance. They will produce errors that are both above and below the accepted value.  Random errors cannot be corrected but can be minimized by doing a large number of observations  Random error always is present

6. ACCURACY  The closeness of a measurement to the accepted value for a specific physical quantity

7. ACCURACY is represented MATHEMATICALLY as ERROR (Relative) or % Difference Accepted Value Mean Experimental Value Absolute Error Absolute Error Relative Error Accepted Value

8. Percent Difference ( %Diff)  When comparing two values or sets of Data to determine error between them, the calculation is called percent difference First calculate the average if using sets of data

9. PRECISION  The agreement of several measures that have been made in the same way with each other  It is also how exact an instrument can measure

10. PRECISION is represented MATHEMATICALLY as DEVIATION (Relative) Mean Experimental Value Each Observed Experimental Value Absolute Deviation done for each measurement Average Absolute Deviation Relative Deviation Mean Experimental Value

11. Example: Deviation and Error

12. Absolute and Relative Error First: CALCULATE THE AVERAGE 8.93m/sec 9.36m/sec 10.48m/sec 9.15m/sec 9.33m/sec 47.25m/sec

13. ABSOLUTE ERROR RELATIVE ERROR

14. Absolute and Relative Deviation Absolute Deviations

15. Absolute and Relative Deviation AVERAGE ABSOLUTE DEVIATION D A 0.52 m/s 0.09 m/s 1.03 m/s 0.30 m/s 0.12 m/s 2.06 m/s

16. Relative Deviation

17. Explain the difference between: Accuracy and Precision AkaError and Deviation You should be able to: In a lab, be able to calculate Error % or % Difference and Deviation % when needed.