Sample standard deviation estimates population standard deviation when population size is large. Sample standard deviation is calculated from few individuals in reference population. Sample standard deviation is always greater than population standard deviation
Sample mean is defined as sum of individual sample means divided by sample size. Sample mean equals population mean when all individual means are equal
Weighted mean differs from ordinary mean by assigning different weights to data points. Equal weights result in same weighted mean as ordinary arithmetic mean. Weighted means can be expressed using coefficients that sum to one
Determine the number of numbers in your sample. Identify the type of data being analyzed. Ensure all numbers are needed for the mean calculation
Variance measures spread between numbers in a data set. Calculated by squaring differences from mean and dividing by total values. Formula: σ² = ∑(xi - x̄)² / N
Both measure variability of figures using mean of a data set. Standard deviation is square root of variance. Variance is average of squared differences from mean