1. Review Problems
Stat 701: Illustrations

2. One-Sample Problem
A sample of 12 radon detectors of a certain type was selected, and each was exposed to 100 pCi/L of radon. The resulting readings were as follows:
105.6, 90.9, 91.2, 96.9, 96.5, 91.3, 100.1, 105.0, 99.6, 107.7, 103.3, 92.4
Problem: To test that the population mean reading is 100, and to construct a confidence interval for this population mean.
Summary: n = 12, Xbar = , S =

3. Two-Sample Problem
The deterioration of many municipal pipeline networks across the country is a growing concern. One technology proposed for pipeline rehabilitation uses a flexible liner threaded through existing pipe. The following data represents the tensile strength (psi) of liner specimens for when a certain fusion process was used and when this process was not used.
The study intended to show that using the fusion process increased the mean tensile strength.

4. Data
No Fusion: 2748, 2700, 2655, 2822, 2511, 3149, 3257, 3213, 3220, 2753
Fused: 3027, 3356, 3359, 3297, 3125, 2910, 2889, 2902

5. Summary of Statistics Descriptive Statistics
Variable N Mean Median StDev SE Mean
NoFusion
Fused

6. Comparative BoxPlots

7. Problems to Demonstrate
Testing Equality of Population Means Using T-Test
Confidence Interval for the Difference of Population Means
Testing Equality of Population Variances
Confidence Interval for the Ratio of Population Variances

8. Testing Equality of Means (Equal Variances)
Two Sample T-Test and Confidence Interval
Two sample T for NoFusion vs Fused
N Mean StDev SE Mean
NoFusion
Fused
95% CI for mu NoFusion - mu Fused: ( -455, 45)
T-Test mu NoFusion = mu Fused (vs <): T = P = DF = 16
Both use Pooled StDev = 249

9. Testing Equality and CI of Means (Unequal Variances)
Two Sample T-Test and Confidence Interval
Two sample T for NoFusion vs Fused
N Mean StDev SE Mean
NoFusion
Fused
95% CI for mu NoFusion - mu Fused: ( -448, 38)
T-Test mu NoFusion = mu Fused (vs <): T = P = DF = 15