Which error influences values consistently in one direction?

• A. Trend
• B. Active Error
• C. Systematic Error
• D. Variation

Answer: (C)

Systematic error is a bias that shifts all measurements in the same direction because of a flaw in the measurement system, such as a miscalibrated instrument or a consistent method bias. This means every result ends up too high or too low by roughly the same amount, affecting accuracy but not just the random spread of values. For example, a scale that reads 0.5 g too high will push all measurements upward by 0.5 g.

A trend describes a gradual change in values over time, which is a temporal pattern rather than a fixed directional bias across the whole dataset. Variation refers to the spread of results due to random error, not a consistent directional shift. Active error involves operator or process mistakes that may be sporadic rather than a persistent bias.