The document compares different models for estimating volatility over time: the equal weight model, EWMA, and GARCH(1,1). The equal weight model treats all past observations equally, while EWMA gives more recent observations greater weight. GARCH(1,1) incorporates mean reversion, making it theoretically more appealing. These models are applied to a portfolio of stocks to estimate volatility on a future date. EWMA produces higher volatility estimates as it weights recent high volatility more. While GARCH(1,1) fits well, the document concludes by questioning which model provides the best volatility estimates.