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Producing Data

3

Introduction

In Chapters 1 and 2, we learned some basic tools of data analysis. We used graphs and numbers to describe data. When we do exploratory data analysis, we rely heavily on plotting the data. We look for patterns that suggest interesting conclusions or questions for further study. However, exploratory analysis alone can rarely provide convincing evidence for its conclusions because striking patterns that we find in data can arise from many sources.

The exploratory data analysisvalidity of the conclusions that we draw from an analysis of data depends not only on the use of the best methods to perform the analysis, but also on the quality of the data. Therefore, Section 3.1 begins this chapter with a short overview on sources of data.

The two main sources for quality data are designed experiments and sample surveys. We study these two sources in Sections 3.2 and 3.3, respectively.

Should an experiment or sample survey that could possibly provide interesting and important information always be performed? How can we safeguard the privacy of subjects in a sample survey? What constitutes the mistreatment of people or animals who are studied in an experiment? These are questions of ethicsethics. In Section 3.4, we address ethical issues related to the design of studies and the analysis of data.