PARALLAX ERROR (noun)

 

The apparent displacement of an object as seen from two different points that are not on a line with the object.

For example, when viewing the meniscus of a liquid within a buret, the eye must be at the exact same level as the meniscus so that the volume scale can be read correctly. If the eye is below the level of the meniscus, parallax error will cause the volume reading to be too small, whereas the reading will be too large if the eye is above the level of the meniscus.

Caution must be taken to eliminate parallax error especially when preparing a standard solution in a volumetric flask.