Random and Systematic Errors

Errors in the measurement process are a common problem. Such errors may fall into two categories: Random and Systematic.

Random errors are the result of inconsistency in the measuring process or variations in the quantity being measured. These result in fluctuations, too high or too low, around the true value.

Consider a scientist measuring the length of an earthworm using a caliper. Inconsistency of the scientist to read the scales correctly, or continuous body movement of the earthworm during the measurement, may result in incorrect length measurements.

Random error cannot be avoided, however, it can be averaged out with repeated trials.

Systematic errors are the results of a persistent issue and lead to a consistent discrepancy in measurement. These errors tend to be either all too high or all too low compared to the true value. For instance, weights being measured using an improperly calibrated weighing balance.

These are predictable and mostly instrument-related. However, unlike random error, it cannot be averaged out with repeated measurement.