Becchetti et al., (2005a) investigated whether inclusion and permanence in the Domini social index affected corporate performance using 1,000 sample firms in a 13 year interval by controlling the size, industry, business cycle and time invariant firm idiosyncratic characteristics. The study explained that social responsibility implied decisions leading to higher cost of labour and of intermediate output, but may also enhance involvement, motivation and identification of the workforce with company goals with positive effects on productivity.