10-68 An article in Knee Surgery, Sport Traumatology, Arthroscopy (2005, Vol. 13, pp. 273-279) considered arthroscopic meniscal repair with an absorbable screw. Results showed that for tears greater than 25 mm, 14 of 18 (78%) repairs were successful, but for shorter tears, 22 of 30 (73%) repairs were successful.
(a) Is there evidence that the success rate is greater for longer tears? Use α = 0.01. What is the P-value?
(b) Calculate a one-sided 90% confidence bound on the difference in proportions that can be used to answer the question in part (a).