The laborer may receive time wages; that is, he may be paid for his labor by the day, or by the week, or by the month, or by the year; or he may receive piecework wages; that is, he may be paid a certain amount for each piece of work which he turns out, the amount which he earns in a day being reckoned by multiplying the number of articles which he has completed by the rate per piece. Two workers of the same ability in different establishments may receive the same piece rate, but turn out different amounts during the same period for the reason that the one factory is equipped with better machinery than the other. Wages which are measured not by the time during which the workers work nor by the number of pieces completed but by the ability of the worker, may be called efficiency wages. It is efficiency wages rather than time wages or piece wages which competition tends to equalize.