Random error

A random error is an error in a measurement that makes the measured values less accurate.

They can be caused by:

• Unexpected Environmental changes (e.g. temperature, humidity, vibrations)
• Limitations of the measuring instrument (e.g. precision limits)
• Human error (e.g. slightly misreading the instrument)
• Other unpredictable factors

How much do random errors affect measurements?

It entirely depends on how well the person doing the experiment is able to use the apparatus, and how well the apparatus is able to measure.

For example, if you’re measuring the length of a table with a ruler that has millimetre markings, you might be able to measure the length to within a few millimetres. However, if you’re using a tape measure that only has centimetre markings, your measurement might only be accurate to within a centimetre or two.

Or, if you get a new intern who failed physics at school to do the measurements, they might not be the most accurate either… because the random error would be higher.

Reducing random errors

To reduce random errors, you can:

• Take multiple measurements and average them
• Use more precise measuring instruments
• make sure the measuring environment is stable (e.g. consistent temperature)
• Train the person doing the measurements to be more accurate
• Calibrate the measuring instruments regularly
• Use digital measuring instruments that reduce human reading errors