Descriptive Statistics

What this video covers

• When median outperforms mean as a measure of central tendency, and how to read left-skewed versus right-skewed distributions from their relationship
• How standard deviation quantifies total risk (systematic plus unsystematic), and what the 68-95-99 rule lets you predict about return ranges
• How correlation coefficients from negative 1 to positive 1 measure co-movement, and why perfect positive correlation eliminates all diversification benefit
• How beta isolates systematic risk relative to a market benchmark of 1.0, and why diversification can reduce standard deviation but never reduce beta
• How alpha measures excess return above what a beta-adjusted model predicts, and whether a positive or negative number indicates manager skill
• Why the Sharpe ratio uses standard deviation (total risk) in its denominator while dividing excess return over the risk-free rate to compare risk-adjusted performance across portfolios
• The exam trap of identifying which statistical measure answers a specific client scenario: outlier-resistant central tendency, total risk forecasting, or risk-adjusted return grading