Garage repair estimates


Use this diagram to explain that pairing reduces the effect of variability between individuals. State that the two distributions overlap considerably because of the variability between the damage for the different cars.

Click on individual crosses. Most estimates are higher for garage A.

Click Show Pairing. Most lines are sloped upwards and most differences are positive — much clearer evidence that the mean estimate is higher for garage A.

An insurance company is concerned that garage A is charging too much for repairing damage to cars. Ten damaged cars were taken to both garage A and another garage for estimates.