When measuring the volume or weight of a mixture, a user reads some variation of scale on the measuring product. Scales are limited to fixed increments of value which are shown by division markings.
It’s impossible to get an exact quantity every time, which is why many operations subject limitations between two values to ensure a product is more consistent than inconsistent. In addition, having a small range supports the safety of the users and those that the product may affect, such as people, crops, and more.
Error in reading scales isn’t primarily targeted toward the user; the same risk occurs with digital measuring tools. No matter how high-tech a digital measuring tool is, there is always a point where the equipment cannot read the smallest standard of deviation.
Especially to new measurement users, the most common reading scale error is the parallax error. The parallax error is the inability to properly align an eye with the part of the scale that a user is reading. The scale’s reading could differ from one person to another because they could be looking at the measuring tool from different angles. Graduated cylinder uncertainty is the most common type of parallax error because of its unique shape.