most analysts determine the values of these parameters on the basis of time series analysis of historical performance data consistent with the dictum that history is a good predictor of the future we note that markowitz himself and associates do not exclude the setting of different values if analysts have good reasons to deviate from historical values fabozzi et al they published the results in an article published in the journal of finance the most prestigious periodical of finance theory barlev and katz barlev and katz defined the reciprocal of average fuel cost per unit of energy input per annum as return indicator and the standard deviation of a years period time series for this indicator as risk