Measurements and their errors

Question 1

Accuracy

Answer 1

A measure of how close a measurement is to the true value.

Question 2

Precision

Answer 2

A measure of how close a measurement is to the mean value. It only gives an indication of the magnitude of random errors, not how close data is to the true value.

Question 3

Random error

Answer 3

Unpredictable variation between measurements that leads to a spread of values about the true value. Random error can be reduced by taking repeat measurements.

Question 4

Systematic error

Answer 4

Causes all readings to differ from the true value by a fixed amount. Systematic error cannot be corrected by repeat readings, instead a different technique or apparatus should be used.

Question 5

Repeatable

Answer 5

The same experimenter can repeat a measurement using the same method and equipment and obtain the same value.

Question 6

Reproducible

Answer 6

An experiment can be repeated by a different experimenter using a different method and different apparatus, and still obtain the same results.

Question 7

Resolution

Answer 7

The smallest change in a quantity that causes a visible change in the reading that a measuring instrument records. (The smallest increment in the input that an instrument can display).

Question 8

Uncertainty

Answer 8

The interval that a value is said to lie within, with a given level of confidence.