From The San Diego Union-Tribune: Research from the National University System Institute for Policy Research says that school construction in California costs 13 percent to 15 percent more when project labor agreements are used. Unions argue that the industry-backed research offers phony results that are intent on discrediting labor agreements. An analysis of the study by the San Diego County Building & Construction Trades Council and others claims that researchers downplayed data that shows no significant difference in the price of school construction when union hiring mandates are in place. The study examined 551 construction projects in 180 California districts between 1996 and 2008. Researchers found that projects operating under labor agreements cost $28.90 to $32.49 more per square foot.