 a measure of how close a measured value is to the “true” value 

 error due to procedural or instrumental factors that cause a measurement to be consistently too large or too small. the error can, in principle, be discovered and corrected (also called systematic error) 

 a type of error, which can be either positive or negative and cannot be eliminated, based on the ultimate limitations on a physical measurement (also called random error) 

 a measure of the reproducibility of a measurement 

 
 a measure of the precision of a measurement 

 the number of significant digits in a quantity is the minimum number of digits needed to express the quantity in scientific notation. in experimental data, the first uncertain figure is the last significant figure. 

 in statistics, the number of independent observations upon which a result is based 

 the range of values within which there is a specified probability that the true value will be found 

 
 theoretical bellshaped distribution of measurements when all error is random. the center of the curve is the mean and the width is characterized by the standard deviation. a normalized curve is also called the “normal curve” 

 the average of a set of all results 

 for a set of data, that value above and below which there are equal numbers of data 

 the difference between the highest and lowest values in a set of data; also called “spread.” with respect to an analytical method, it is the concentration interval over which the linearity, accuracy, and precision are all acceptable. 

 a statistic measuring how closely data are clustered about the mean value. 

pooled standard deviation 
 
 
 statistical test used to decide whether to discard a datum that appears discrepant 

 statistical test used to decide whether the results of two experiments are within experimental uncertainty of each other. the uncertainty must be specified to within a certain probability. 

 a statistical tool used to express confidence intervals to compare results from different experiments 

 the square of standard deivation 
