Carpal tunnel syndrome is a common wrist complaint resulting from a compressed n
ID: 3230501 • Letter: C
Question
Carpal tunnel syndrome is a common wrist complaint resulting from a compressed nerve, and it is often caused by repetitive wrist movements. In a randomized controlled trial, among 73 patients treated with surgery and evaluated one year later, 67 were found to have successful treatments. Among 83 patients treated with splints and evaluated one year later, 60 were found to have successful treatments (based on data from "Splinting vs Surgery in the Treatment of Carpal Tunnel Syndrome, " by Gerritsen, et al., Journal of the American Medical Association, Vol. 288, No. 10). In a journal article about the trial, authors claimed that treatment with open carpal tunnel release surgery resulted in better outcomes than treatment with wrist splinting for patients with CTS (carpal tunnel syndrome)". Use a 0.01 significance level to test the stated claim What treatment strategy is suggested by the results?Explanation / Answer
Solution:
Here, we have to use Z test for two population proportions.
H0: p1 = p2
Ha: p1 > p2
This is a one tailed – upper tailed – right tailed test.
We are given
Level of significance = alpha = 0.01
X1 = 67
N1 = 73
X2 = 60
N2 = 83
P1 = X1/N1 = 67/73 = 0.917808219
P2 = X2/N2 = 60/83 = 0.722891566
The test statistic formula is given as below:
Z = (P1 – P2) / sqrt[(P1*(1 – P1)/N1)+(P2*(1 – P2)/N2)]
Z = (0.92 - 0.72)/sqrt[(0.92*0.08/73)+(0.72*0.28/83)]
Z = 3.1226
Upper critical value = 2.3263
P-value = 0.0009
P-value < Alpha = 0.01
So, we reject the null hypothesis that both proportions are same.
There is sufficient evidence to conclude that the treatment with open carpal tunnel release surgery resulted in better outcomes than treatment with wrist splinting for patients with CTS.