GammaDistribution data can be approximated by a lognormal distribution:
Comparing log-likelihoods with estimation by gamma distribution:
Lognormal distribution was traditionally used to analyze the fractional stock price changes from the previous closing price. Find the estimated distribution for the daily fractional price changes of the S&P 500 index from January 1, 2000 to January 1, 2009:
To fit lognormal distribution, all data must be positive:
Compare the histogram of the data with the PDF of the estimated distribution:
Find the probability of the fractional price change being greater than 0.5%:
Find the mean fractional price change:
Simulate fractional price changes for 30 days:
Show that using
LogisticDistribution provides better fit than using lognormal distribution:
Lognormal distribution can be used to model stock prices:
Fit the distribution to the data:
Compare the histogram to the PDF:
Find the probability that the price is above $500:
Find the mean price:
Simulate the price for the consecutive 30 days:
Lognormal distribution can be used to approximate wind speeds:
Find the estimated distribution:
Compare the PDF to the histogram of the wind data:
Find the probability of a day with wind speed greater than 30 km/h:
Find the mean wind speed:
Simulate wind speeds for a month:
The fractional change of stock price

at time

(in years) is assumed lognormally distributed with parameters

and

:
Compute expected stock price at epoch

:
Assuming an investor can invest money for a year at a continuously compounded yearly rate

risk-free, the risk-neutral pricing condition requires:
Solve for parameter

:
Consider an option to buy this stock a year from now, at a fixed price

. The value of such an option is:
The risk-neutral price of the option is determined as the present value of the expected option value:
Assuming rate

of 5%, volatility parameter

of 0.087, an initial price of $200 per share of stock, and a strike price of $190 per share, the Black-Scholes option price is: