...
The VIX is calculated as the square root of the par variance swap rate for a 30-day term[clarify] initiated today. https://en.wikipedia.org/wiki/VIX
The VIX is quoted in percentage points and represents the expected range of movement in the S&P 500 index over the next year, at a 68% confidence level (i.e. one standard deviation of the normal probability curve). For example, if the VIX is 15, this represents an expected annualized change, with a 68% probability, of less than 15% up or down. One can calculate the expected volatility range for a single month from this figure by dividing the VIX figure of 15 not by 12, but by √12 which would imply a range of +/- 4.33% over the next 30-day period. [7] Similarly, expected volatility for a week would be 15 divided by √52, or +/- 2.08%.
http://www.investopedia.com/terms/v/volatility.asp - In finance, volatility is the degree of variation of a trading price series over time as measured by the standard deviation of returns.
Historic volatility is derived from time series of past market prices. An implied volatility is derived from the market price of a market traded derivative (in particular an option). The symbol σ is used for volatility, and corresponds to standard deviation, which should not be confused with the similarly named variance, which is instead the square, σ2.
We ended up discussing the need for a general definition of standard deviation as a kind of statistical measure, as well as variance as a statistical measure, and then to revise the definition of volatility according to better sources for the definition as well as referencing these concepts, as appropriate. Greg Russell at SS may be able to assist with this as well.
(4) We also briefly discussed the notion of a settlement period, which one of the definitions references, which should probably be defined in FBC where we define trade.
(5) Pete raised the question of how we incorporate British spellings, such as the difference between the US "tradable" vs. UK "tradeable", both of which are considered correct depending on the dictionary. One option would be to have two rdfs:label annotations, which include the language tags, and another would be to use skos:altLabel, although the language tagged label is likely preferable. Elisa suggested that Pete write this up in the wiki for an FLT discussion.
Decisions