Typically sensor readings have a degree of error or uncertainty. Having higher sensor accuracy (lower uncertainty/error) is better for analysis or reaisning, but there is always some innaccuracy, so some form of reasoning with uncertainty is usually required. Sensor accuracy may be measured in terms of standard deviation for numeric data or probability of being correct (precision) for categorical data, but the exact way will depend on details of the sourec of the data and its intended purpose.
Used on Chap. 15: page 353