The two-week old strike by union mechanics at Northwest Airlines has put the role of unions in the national spotlight. A recent nationwide study commissioned by employers looked at why employees choose to unionize in the first place -- and the results are somewhat surprising. Gantz Wiley, a Minneapolis research firm, surveyed workers in industries across the board. Researcher Kyle Lunby says that intangible issues like *fair treatment on the job* are important in the decision to join a union.