The primary symbol for the variance of a probability distribution is σ2.
The variance, denoted by σ2 (sigma squared), quantifies the spread or dispersion of a set of data points around their mean (average) value. In probability and statistics, it specifically measures the expected squared deviation of a random variable from its mean. A higher variance indicates that the data points are more spread out, while a lower variance suggests they are clustered more closely around the mean.
Here's a breakdown of related symbols and concepts:
- σ2: Variance of a population. This is the most common symbol for variance.
- s2: Sample variance. This represents the variance calculated from a sample of the population, used to estimate the population variance.
- Var(X): Another notation for the variance of a random variable X.
- σ: Standard deviation, which is the square root of the variance (σ = √σ2). The standard deviation provides a measure of spread in the same units as the original data, making it often more interpretable than the variance.
In summary, while other notations exist, σ2 is the most recognized and universally used symbol for the variance of a probability distribution.
