STATS4GIRLS
 

Formulas & Definitions are in alphabetical order


Empirical Rule ~ aka 65-95-99.7 Rule

When the bulk of the data clusters around the mean in a normal distribution (or bell-shaped curve), the standard deviation can be used to approximate how much of the data will cluster around the mean. 


  1. -65% of the data values will fall within 1 standard deviation from the mean

  2. -95% of the data values will fall within 2 standard deviations from the mean

  3. -99.7% of the data values will fall within 3 standard deviations from the mean



























Factorial

The result of multiplying a series of descending natural numbers; useful in computing the number of combinations or permutations between











Mean

The average of a sample









Median

The midpoint of a ranked dataset









Midrange

The midpoint is the midrange between the highest and lowest data points.












Mode

Most frequently occurring value of x









Sample Variance

The mean of the squared deviations (using the degrees of freedom as the denominator) in a sample





















Standard Deviation

Standardized measurement of dispersion or variation around the mean












Standard Deviation of a Sample

The positive square root of the variance in a sample