Selectivity is the same as Jensen's alpha
Selectivity(Ra, Rb, Rf = 0, ...)
Ra | an xts, vector, matrix, data frame, timeSeries or zoo object of asset returns |
---|---|
Rb | return vector of the benchmark asset |
Rf | risk free rate, in same period as your returns |
… | any other passthru parameters |
$$Selectivity = r_p - r_f - \beta_p * (b - r_f)$$
where \(r_f\) is the risk free rate, \(\beta_r\) is the regression beta, \(r_p\) is the portfolio return and b is the benchmark return
Carl Bacon, Practical portfolio performance measurement and attribution, second edition 2008 p.78
data(portfolio_bacon) print(Selectivity(portfolio_bacon[,1], portfolio_bacon[,2])) #expected -0.0141#> [1] -0.01416944data(managers) print(Selectivity(managers['1996',1], managers['1996',8]))#> [1] 0.08077871print(Selectivity(managers['1996',1:5], managers['1996',8]))#> HAM1 HAM2 HAM3 HAM4 HAM5 #> Jensen's Alpha (Risk free = 0) 0.08077871 NA 0.2196026 0.06063837 NA