Accuracy and Precision Self-Quiz

Define accuracy.

Define precision.

John measures the mass of a rock and finds it to be 12.21 kg. He states that his measurement is both accurate and precise. For what two reasons is his statement incorrect?

Wendy is using a poorly calibrated electronic balance to measure the mass of a crucible. Her technique in making the measurement is very careful and she repeats it three times. What will likely characterize her measurements?

• high accuracy and high precision

• high accuracy and low precision

• low accuracy and high precision

• low accuracy and low precision

Which student’s measurements have high precision but low accuracy?

• Nicole

• Matthew

• Leonard

Which student’s measurements are both accurate and precise?

• Nicole

• Matthew

• Leonard

Calculate the average of Matthew’s three measurements. Comment on his accuracy and precision.

The deviation of a measurement is defined as the absolute value of the difference between that particular measurement and the average value. Deviation = |measured value – average value| Calculate the deviations for each of Kaitlyn’s density measurements.

The average deviation is the sum of each individual deviation divided by the total number of measurements. Calculate the average deviation for Kaitlyn’s experiment.

What conclusion can be drawn from an experiment in which the average deviation is very small?

• The measurements are accurate.

• The measurements are precise.

• The measurements are both accurate and precise.

• No conclusions about either accuracy or precision can be made.