COST ESTIMATION Cost Indexes Present Cost=(original cost at time t)* • Marshall and Swift. 1. All industryequipment index. Arithmetic average of 47 equipment types. 2. Processindustry equipment index. Weighted average of 8 of these: cement 2% paint 5% chemicals 48% paper 10% clay products 2% petroleum 22% glass 3% rubber 8% MS was 100 in 1926.