Question

A study of the surface roughness of coated interior pipe used in oil fields was conducted. The data in micrometers) for 20 sampled pipe sections are reproduced in the table below whether the median surface roughness of coated interior pipe, n, differs from 2 micrometers. Test using a=0.10. 1.87 2.65 2.48 1.42 1.98 1.35 2.65 2.76 2.78 2.75 Full data set 2.01 2.59 1.47 2.35 1.72 2.35 1.86 2.25 2.65 2.24 What are the null and alternative hypotheses? O A. Ho: 1-13 Han<13 OD. Ho: n=13 H: > 13 OB. Hon - 2 Hy:n<2 OE Hon=7 H:7 06. Ho | #7 H:17 OF. Hy: 19 = 2 H:12 What is the fest statistic for this test? The test statistic is What is the p-value for this test? (Round to the nearest thousandth as needed.) What is the conclusion for this test? Ho. There is evidence to indicate the median surface roughness of coated interior pipe differs from 2 micrometers at 0.10

Answer 1

Using Minitab,

1. Open the sample data,
2. Open the 1-Sample Sign dialog box.
   • Statistics > 1-Sample Inference > Sign
   • STATISTICS > One Sample > Sign
3. In Sample, enter %
4. Select Perform hypothesis test.
5. In Hypothesized median, enter 18.
6. Click OK.

MTB > STest 2 data! SUBC> Alternative -1. Sign Test for Median: data Sign test of median = 2.000 versus < 2.000 Below data N 20 Equal 0 7 Above 13 Р 0.9423 Median 2.300 MTB > let c2=median (c1) MTB Σ + C3 C1 data C4 C2 median C5 C6 C7 C8 C9 C10 G 1 1.87 2.3 2. 2.65 3 2.48

The null hypothesis states that the median equals 2. Because the p-value is approximately 0.9423, which is greater than the significance level of 0.05, we cannot reject the null hypothesis.