Introduction

Types of Data

• Categorical
  • Nominal (cannot be ordered)
  • Ordinal (can be ordered)
• Numerical
  • Discrete (correspondent to integers)
  • Continuous

Mean

$$\bar{x}=\frac{1}{n}\sum _{i=1}^n{x}_i$$

Variance

$$s_{n-1}^2=\frac{1}{n-1}\sum _{i=1}^n(x_i-\bar{x}{)}^2$$

Variance describes the dispersion or spread of the data since $a=\bar{x}$ minimizes ${\sum }_{i=1}^n(x_i-a{)}^2$

Standard Variation

$$s_{n-1}=\sqrt{s_{n-1}^2}$$