The manager of a tea estate reports that the green leaf brought in this year stands 22 in every hundred above last year's total, and credits the new plucking method introduced in January. Which of the following, if true, most weakens the manager's claim?

The rise is measured from a year that was not an ordinary year, and simply working the full season again restores very nearly the whole 22 in every hundred. A base as low as that will manufacture a rise for any method whatever, including no method at all. Who trained the workers and where the tea is auctioned bear on nothing, and an unchanged weighbridge, far from weakening the claim, removes one small doubt about it.