Which of the following is not false about annual risk of TB

Incidence of TB infection (Annual infection rate, Annual risk of Infection ARI) : Percentage of population under study who will be newly infected (not diseased or cases) with TB among Non-infected in 1 year. Expresses attacking force of TB in community In developing countries 1% ARI corresponds to: 50 SS +ve cases per 100,000 general population Tuberculin conversion index is the "best indicator for evaluation of TB problem and its trend" in the community. Current ARI in India : 1.5% Ref: Park 25th edition Pgno : 190-191