# Descriptive statistics, sampling methods, and variables

## Keeping content fresh

**Mean**

**Median**

**Mode**

**Variance**

**Standard deviation**

**Interquartile range**

**Simple random sampling**

**Stratified random sampling**

**Clustered random sampling**

**Purposive sampling**

**Convenience sampling**

**Nominal variables**

**Interval variables**

**Ratio variables**

**Count variables**

**Hierarchical regression**