Caclulate a Lower Partial Moment around the mean or a specified threshold.
lpm(R, n = 2, threshold = 0, about_mean = FALSE)
xts data
the n-th moment to return
threshold can be the mean or any point as desired
TRUE/FALSE calculate LPM about the mean under the threshold or use the threshold to calculate the LPM around (if FALSE)
Lower partial moments capture negative deviation from a reference point. That reference point may be the mean, or some specified threshold that has other meaning for the investor.
Huffman S.P. & Moll C.R., "The impact of Asymmetry on Expected Stock Returns: An Investigation of Alternative Risk Measures", Algorithmic Finance 1, 2011 p. 79-93