1 Accuracy and Precision At the conclusion of our time together, you should be able to: 1. Explain the difference between the accuracy and precision 2. Give examples of accuracy and precision

2 Scientific Inquiry:Collecting and Analyzing Data EQ: How can data be graphed and analyzed?

3 Copyright © Houghton Mifflin Harcourt Publishing Company What are some characteristics of good data collection? Experiments can be verified by repetition and replication. Results must be accurate and precise

4 Data l Data is any information collected in an experiment or investigation l Data must be collected correctly in order to be accepted by scientists. Data must be two things: 1. Accurate 2. Precise

5 Replication vs. Repetition Repetition is when the same scientist completes multiple trials.

6 Replication vs. Repetition Replication is when a different scientist completes the experiment by following the procedures. Replication is done to get same/similar results which in create the validity of experiment.

7 Characteristics of good measurements?  Scientists use two words to describe how good the measurements are:  Accuracy- how close the measurement is to the actual value (number).  Precision- how close a group of measurements are to each other.

8 In a Couple Words Accuracy - correctness ( accu – RIGHT) Precision – reproducibility (REPEATABLE)

9 Let’s use a golf analogy

10 Precision l Which set is more precise? 18.2, 18.4, , 18.3, , 17.2, 19.44

11 Example: Accuracy l 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

12 Accurate?No Precise?Yes

13 Accuracy vs. Precision High Accuracy High Precision Low Accuracy

14 Three targets with three arrows each to shoot. Can you hit the bull's-eye? Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare? Can you define accuracy vs. precision?

15 Accurate? Yes Precise?Not enough info

16 Accurate?Yes Precise?Yes

17 Precise?No Accurate?Somewhat

18 Accurate?Yes Precise?We can’t say!

19 In terms of measurement  Three students measure the room to be 10.2 m, 10.3 m and 10.4 m across. The actual distance was m.  Were they precise?  Were they accurate?

20 Learning log: Evaluate whether the following are precise, accurate or both. Low Accuracy Low Precision Low Accuracy High Precision High Accuracy High Precision AB C

21 Lets look at measuring!

22  When we measure something, we can (and do) always estimate between the smallest marks.  What we record is SIGNIFICANT cm

23  The smaller the increments of the instrument, the better we can estimate.  Scientists understand that the last number measured is actually an estimate cm

24  The measurements we write down tell us about the precision of the instrument.  The last digit is between the lines  How would you describe this length?  cm (really?) cm