Accuracy and PrecisionAccuracy and Precision

Precision reflects the Precision reflects the reproducibility of a given type of reproducibility of a given type of measurementsmeasurements

(same answer)(same answer)

Accuracy reflects how close a Accuracy reflects how close a group of measurements are to group of measurements are to an accepted value an accepted value

(right answer)(right answer)

The dart throws The dart throws reflect reflect measurements measurements that are:that are:

precise precise not accuratenot accurate

The dart throws The dart throws reflect reflect measurements measurements that are:that are:

accurate accurate preciseprecise

This dart board This dart board reflects reflects measurements measurements that are:that are:

not accurate not accurate not precisenot precise

Student A

7.3 9.4 8.3

Student B

8.2 8.1 8.0

Student C

8.8 8.6 8.9

Which student had the best lab technique?

What could you say about Student B’s lab technique?

What is evident about Student A’s lab technique?

Actual density of copper = 8.94 g/cm3

Not accurateNot precise

Not accuratePrecise

AccuratePrecise

Student C

Makes the same mistake over and over

Sloppy in his measurements

Density Data Collected by Three Different Students

Student A Student B Student C

Trial 1 1.54 g/cm3 1.40 g/cm3 1.70 g/cm3

Trial 2 1.60 g/cm3 1.68 g/cm3 1.69 g/cm3

Trial 3 1.57 g/cm3 1.45 g/cm3 1.71 g/cm3

Average 1.57 g/cm3 1.51 g/cm3 1.70 g/cm3

Actual density = 1.59 g/cm3

Which lab group measured the volume of the liquid with the most precision?

The table shows four mass readings of one object as measured by four different balances. Which balance produced the most precise measurements?

actual mass = 25.00 g

These data were gathered by four groups of students. Each group performed four trials to test the acceleration rate of a toy car. Which group had the most precise data?