Accuracy and Precision Qualitative Measurements Qualitative measurements give

Accuracy and Precision

Qualitative Measurements –Qualitative measurements give results that are descriptive and non-numerical. • Example: Colors, smells

Quantitative Measurements –Quantitative measurements give results that are definite, usually as numbers and units. • Example: 27 m. L

Accuracy and Precision • Measurements work best when they are accurate and precise

Accuracy • Accuracy is a measure of how close a measurement comes to the actual or true value of whatever is measured. • To evaluate the accuracy of a measurement, it must be compared to the correct value.

Precision • Precision is a measure of how close a series of measurements are to one another. • The precision of a measurement depends on more than one measurement.

Accuracy and Precision Accuracy • Reproducibility • Correctness • Check by repeating • Check by using measurements different methods (Trials) • Poor accuracy results from • Poor precision procedural or results from poor equipment flaws technique

Accuracy and Precision

Accuracy and Precision • In this picture, all of the darts land on the bullseye which illustrates good precision and accuracy. • In this picture, all of the darts land near each other, but away from the bulls-eye which illustrates good precision, but poor accuracy.

Accuracy and Precision • Here the darts are not close to each other, but are close to the bulls-eye indicating poor precision, but good accuracy. • Finally, the darts are not close to each other or near the bulls-eye indicating both poor accuracy and poor precision.

Accuracy and Precision • What is the following an example of: • You did an experiment to see at what degree water boiled in Celsius. You got the following results. T 1 - 65 T 2 - 67 T 3 – 66 Accuracy or Precision? ? 99. 98 C

Accuracy and Precision A basketball player throws 100 free-throws; 95 of these balls go through the goal; 5 miss the goal entirely. Describe the precision and accuracy of the free-throws. Both

Accuracy and Precision The same player is having an off day; 5 balls go through the goal; the other 95 balls bounce off of the rim. Describe the precision and accuracy of the throws. Precise, but not accurate

Accuracy and Precision • Each of five students used the same ruler to measure the length of the same pencil. The results are as follows: 15. 33 cm, 15. 34 cm, 15. 33 cm, 15. 34 cm. The actual length of the pencil was 15. 85 cm. Describe whether accuracy and precision are each good or poor for these measurements.

Draw a target diagram that shows precision but not accuracy.

Draw a target diagram that shows accuracy but not precision

Draw a target diagram that shows both accuracy and precision

Practice a)78. 1 m. L, 43. 9 m. L, 2 m. L (should be 100 m. L) Precise, Accurate, Both, Neither b) 68. 1 m. L, 68. 2 m. L, 68. 0 m. L (should be 68. 1 m. L) Precise, Accurate, Both, Neither c) 98. 0 m. L, 98. 2 m. L, 97. 9 m. L (should be 100 m. L) Precise, Accurate, Both, Neither d) 72. 0 m. L, 60. 3 m. L, 68. 1 m. L (should be 100 m. L) Precise, Accurate, Both, Neither