Calculating implied volatility can be difficult if you dont have a spreadsheet handy. Fortunately, many tools are available on the web to perform the calculation; for example, www.option-price.com contains several option calculators, including one for implied volatility. Using daily price data from finance.yahoo.com, calculate the annualised standard deviation of the daily percentage change in a stock price. For the same stock, use these websites to find the implied volatility. Option price data can be retrieved from www.cboe.com . Recalculate the standard deviation using 3 months, 6 months and 9 months of daily data. Which of the calculations most closely approximates implied volatility ? What time frame does the market seem to use for assessing stock price volatility ?