Answer:
Market Dominance.
Step-by-step explanation:
I believe that the best metric to evaluate in such a situation would be Market Dominance. In other words, the percentage of dominance that Carrefour has in its own market, in comparison to the rest of the competition such as Wal-Mart and Tesco. This would allow management to see if they have lost, maintained, or gained market dominance in this period of time which will in term give them an idea of their performance within the market and whether or not they should be worried about the competition.