Fundamentals of Quality Control and Improvement, 4th Edition

5Data Analyses and Sampling

1. 5-1 Introduction and Chapter Objectives
2. 5-2 Empirical Distribution Plots
3. 5-3 Randomness of a Sequence
4. 5-4 Validating Distributional Assumptions
5. 5-5 Transformations to Achieve Normality
6. 5-6 Analysis of Count Data
7. 5-7 Analyses of Customer Satisfaction Data
8. 5-8 Concepts in Sampling
9. Summary

Symbols
	Sample average
s	Sample standard deviation
n	Sample size
Xi	ith observation in a sample
sm	Standard deviation of the sample median
F(x)	Cumulative distribution function
M	Median
Q1	First quartile
Q3	Third quartile
IQR	Interquartile range

5-1 Introduction and Chapter Objectives

In this chapter we continue to expand on the various descriptive and inferential statistical procedures described in Chapter 4. Our objective is to analyze empirical data graphically since they provide comprehensive information and are a viable tool for analysis of product and process data. The information they provide on existing product or process characteristics helps us determine whether these characteristics are close to the desired norm. A second objective is to test for distributional assumptions. Recall that in Chapter 4, for testing hypothesis on various parameters such as the population mean or variance, the assumption of normality was made. We present a method for testing the validity of such an assumption. Further, we discuss some transformations ...