Mean and Related Functions

The arithmetic mean m of a population of values x with n members is given by  

The standard deviation quantifies how much the values vary from one another, whereas SEM quantifies how precisely you know the true mean. If you want to show the variability of biological values, use SD. For characterizing of the precision of an in vitro experiment, SEM is the best expression. 

The absolute error of mean EM is calculated from formula 

If the observed data follow a bell-shaped Gaussian (normal) distribution, the confidence interval Cl of mean is defined by 

N number of data xi P probability of significant deviation of a value from data within interval confidence t - borders of the (1 - P)th part of the area of the Gaussian distribution for a given F. 

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