RE: Volatility Index by Wilder jr.

[Gary Funck <gary@xxxxxxxxxxxx>]

Welder's volatility index is essentially a short-term EMA (about 7 days) of
the True Range. It is worth noting when reading Wllder's work that something
he calls an N-day smoothed moving average we would now call an (N + 1)/2 day
EMA. So, Wilder's fomulation:
   VSI = (13 * VSI[-1] + TR)/14
is weighting the new value of TR by 1/14, and this works out to about a 7
day EMA,
by today's interpretation.