Statistics Used
in Manager/Advisor Analysis
The following provides a brief
description of each statistic used in our analysis and gives the formula used
to calculate each. Annualized statistics are based on monthly data, unless
Quarterly data is specified.
Value Added
Monthly Index (VAMI) - This index reflects the growth
of a hypothetical $1,000 in a given investment over time. The index is equal to
$1,000 at inception. Subsequent month-end values are calculated by multiplying
the previous months VAMI index by 1 plus the current month rate of
return.
Where Vami 0=1000 and
Where R
N=Return for period N
Vami
N=( 1 + R N
) ´ Vami N-1
Compound (Geometric) Average
Return - The geometric mean is the monthly average return
that assumes the same rate of return every period to arrive at the equivalent
compound growth rate reflected in the actual return data. In other words, the
geometric mean is the monthly average return that, if applied each period,
would give you a final Vami (growth) index that is equivalent to the actual
final Vami index for the return stream you are considering. Annualized compound
quarterly and annualized returns are calculated using the compound monthly
return as a base.
Where N=Number of
periods
Where Vami
0=1000
Compound Monthly ROR=( Vami N ¸ Vami 0 ) 1/ N
- 1
Compound Quarterly ROR=( 1 + Compound Monthly ROR ) 3
- 1
Compound Annualized
ROR=( 1 + Compound Monthly ROR
) 12
- 1
Standard Deviation
- Standard Deviation measures the
dispersal or uncertainty in a random variable (in this case, investment
returns). It measures the degree of variation of returns around the mean
(average) return. The higher the volatility of the investment returns, the
higher the standard deviation will be. For this reason, standard deviation is
often used as a measure of investment risk..
Where R
I=Return for period I
Where M R=Mean of return
set R
Where N=Number of
Periods
N
M R =(
S R I ) ¸
N
I=1
N
Standard Deviation=( S ( R I
- M R ) 2 ¸ (N - 1) ) ½
I=1
Annualized Standard
Deviation
Annualized Standard
Deviation=Monthly Standard Deviation ´ ( 12 )
½
Annualized Standard Deviation *
=Quarterly Standard Deviation ´ ( 4 ) ½
* Quarterly
Data
M G = (
S G I )
¸ N
G
I=1
Downside Deviation - Similar
to the loss standard deviation except the downside deviation considers
only returns that fall below a defined Minimum Acceptable Return (MAR)
rather then the arithmetic mean. For example, if the MAR were assumed
to be 10%, the downside deviation would measure the variation of each
period that falls below 10%. (The loss standard deviation, on the other
hand, would take only losing periods, calculate an average return for
the losing periods, and then measure the variation between each losing
return and the losing return average).
Where R I=Return for
period I
Where N=Number of
Periods
Where R MAR=Period
Minimum Acceptable Return
Where L I=R
I - R MAR ( IF R I
- R MAR < 0
)or 0 ( IF R I - R MAR
³ 0 )
N
Downside Deviation=( (S ( L I ) 2
) ¸ N )
½
I=1
Downside Deviation = (
(S ( L I )
2 ) ¸ N ) ½
I
Where NL=Number of
Periods where R I - M < 0
N
Sharpe Ratio - A
return/risk measure developed by William Sharpe. Return (numerator)
is defined as the incremental average return of an investment over the
risk free rate. Risk (denominator) is defined as the standard deviation
of the investment returns.
Where R I=Return for
period I
Where M R=Mean of
return set R
Where N=Number of
Periods
Where SD=Period Standard
Deviation
Where R RF=Period Risk
Free Return
N
M R =(
S R I ) ¸
N
I=1
N
SD=( S ( R I - M R )
2 ¸ (N
- 1) )
½
I=1
Sharpe Ratio=( M R - R
RF ) ¸ SD
Annualized Sharpe Ratio
Annualized Sharpe=Monthly
Sharpe ´ ( 12 ) ½
Annualized Sharpe * =Quarterly Sharpe ´ ( 4 )
½ * Quarterly Data
Sortino Ratio - This is another return/risk ratio developed by Frank
Sortino. Return (numerator) is defined as the incremental compound average
period return over a Minimum Acceptable Return (MAR). Risk (denominator)
is defined as the Downside Deviation below a Minimum Acceptable Return
(MAR).
Where R I=Return for
period I
Where N=Number of
Periods
Where R MAR=Period
Minimum Acceptable Return
Where DD MAR=Downside
Deviation
Where L I=R
I - R MAR ( IF R I
- R MAR < 0
)or 0 ( IF R I - R MAR
³ 0 )
N
DD MAR=( (S ( L I )
2 )
¸ N )
½
I=1
Sortino Ratio=( Compound Period Return - R MAR ) ¸ DD MAR
Annualized Sortino
Ratio
Annualized Sortino=Monthly
Sortino ´ ( 12 ) ½
Annualized Sortino* =Quarterly Sortino ´ ( 4 )
½
* Quarterly
Data
Calmar Ratio -
This is a return/risk ratio. Return (numerator) is
defined as the Compound Annualized Rate of Return over the last 3 years. Risk
(denominator) is defined as the Maximum Drawdown over the last 3 years. If
three years of data are not available, the available data is used. ABS is the
Absolute Value.
Sterling Ratio - This is a return/risk ratio. Return (numerator) is defined as the
Compound Annualized Rate of Return over the last 3 years. Risk (denominator) is
defined as the Average Yearly Maximum Drawdown over the last 3 years less an
arbitrary 10%. To calculate this average yearly drawdown, the latest 3 years
(36 months) is divided into 3 separate 12-month periods and the maximum
drawdown is calculated for each. Then these 3 drawdowns are averaged to produce
the Average Yearly Maximum Drawdown for the 3-year period. If three years of
data are not available, the available data is used.
Where D1 Calmar
Ratio = Compound Annualized ROR ¸ ABS (Maximum Drawdown)
= Maximum Drawdown for
first 12 months
Where D2 = Maximum
Drawdown for next 12 months
Where D3 = Maximum
Drawdown for latest 12 months
Average Drawdown = ( D1 +
D2 + D3 ) ¸ 3
Sterling Ratio =
Compound Annualized ROR ¸ ABS ( (Average Drawdown - 10% ))
Drawdown -
Drawdown is any losing period during an investment record. It is defined as the
percent retrenchment from an equity peak to an equity valley. A Drawdown is in
effect from the time an equity retrenchment begins until a new equity high is
reached. (i.e. In terms of time, a drawdown encompasses both the period from
equity peak to equity valley (Length) and the time from the equity valley to a
new equity high (Recovery).
Maximum Drawdown is simply the largest percentage
drawdown that has occurred in any investment data record.