Table 1: Comparison of traditional measures.

Refs.Up to yearMethodFormulaDynamic characteristics

Birnbaum [13]1969Birnbaum importance measureDynamic
Barlow and Proschan [4]1975Barlow-Proschan importance measureDynamic
Griffith [15]1980Griffith importance measureDynamic
Natvig [29]1982Natvig importance measureStatic with the mean lifetime and repair time
Wu [17] 2005Wu importance measureStatic
Si et al. [1]2012Integrated importance measureDynamic