Another example is that education is a strong signal in labor market. high education level would stand for high productivity because both entail more intelligence,more motivation,more self-discipline,more energy and hard work. Thus firms are correct in considering education a signal of productivity. Another example is that education is a strong signal in labor market. high education level would stand for high productivity because both entail more intelligence, more motivation, more self-discipline, more energy and hard work. Thus firms are correct in considering education a signal of productivity