In general terms, key sectors analysis aims at identifying and quantifying the economic impact of a sector in a given economy. For a sector, we mean here either an industry or a region, or even a cluster of them. Quite a few measures and methodologies of varied complexity have been proposed in the literature, from multiplier sums to extraction methods, but not without debate about their properties and information content. All of them, to our knowledge, focus exclusively on the interdependence effects that result from an input-output structure of the economy. By so doing the approach misses critical links beyond the interindustry ones. A productive sector's role is that of producing but also that of generating and distributing income among primary factors and households as a result of production. Thus, when measuring a sector's role, the income generating process should not be omitted if we want to elucidate the sector's true economic impact. A simple way to make the missing income links explicit is to use the SAM (Social Accounting Matrix) facility. Extending an extraction methodology to the SAM we compare lost output with and without the missing links. We observe that substantial differences in sectoral lost gross output arise but, even more important, we capture the implied shifting in the rank ordering of sectors.
