Precise vs. Accurate

Precise and accurate are both adjectives that describe measurements. They can be used in conjunction (a measurement can be both precise and accurate) or in opposition (a measurement can be precise but not accurate, and vice versa).

Precise means an exact measurement taken to a very small degree of variance. It helps ensure accuracy, but it is no guarantee. For example, a caliper will give you a more precise reading than a tape measure will, but if you use it incorrectly the results may not be accurate. In mathematical measurements, smaller decimal values are considered more precise; therefore, 12.10 g is more precise than 12 g.

Accurate, on the other hand, means correct or free from errors, without regard to the level of precision. The level of what is considered accurate often depends on the situation. If a friend asks how much you spent on a shirt, it could be considered accurate to respond "$20." But if a cashier asks you to pay for the shirt, they must request a more accurate "$19.88."

In science, it is important to be both accurate and precise. A lack of precision can lead to results that appear to be accurate but are not.