Variance and standard deviation measure the dispersion of a set of data points around its mean value. There are different formulas for population and sample variance & standard deviation. This is due to the fact that the sample formulas are the unbiased estimators of the population formulas. More on the mathematics behind it.

1- Types of data and level of measurement
2- Graphs and Tables that Represent Categorical Variables
3- Excel formulas
4- Graphs and tables that represent numerical variables
5- Graphs and Tables for Relationships Between Variables.
6- Mean, Median, Mode
7- Variance and Standard Deviation
8- Covariance and Correlation
9- Distributions
10- The Central Limit Theorem
11- Estimators and Estimates
12- Confidence Intervals and the Margin of Error
13- Studentâ€™s T Distribution
14- Formulas for Confidence Intervals
15- Scientific method
16- Hypotheses
17- Decisions You Can Take
18- Statistical Errors (Type I Error and Type II Error)
19- P-Value
20- Formulae for Hypothesis Testing
21- Basics
22- Linear regression equation
23- How to do linear regression in Excel with Analysis ToolPak
24- Interpret regression analysis output
25- How to make a linear regression graph in Excel
26- How to do regression in Excel using formulas