Suppose that in a gravimetric analysis, you forget to dry the filter crucibles before collecting precipitate. After filtering the product, you dry the product and crucible thoroughly before weighing them. Is the apparent mass of product always high or always low? Is the error in mass systematic or random?

• Systematic errors are mistakes that are not caused by chance, but rather by an inherent inaccuracy in the system (including either the observation or measurement process). The term "systematic error" can also refer to a mistake with a nonzero mean that has no impact when the observations are averaged.
• The term "random error" refers to an unanticipated disruption in the experiment caused by an unknown source. In theory, you may track down the cause of the mistake and eliminate it in a better trial, bringing the measured mean closer to the real mean. Random mistake can be either beneficial or harmful, and it can't be avoided.

First, because the source of the error can be identified and corrected in the next experiment, this error is systematic.

Because the mass of the dry crucible is smaller than the mass of the crucible plus the moisture, the product's mass will be low.