BASIC STATISTICAL CONCEPTS
How to design experiments and analyze data is the subject of this book. A small handful of statistical ideas and techniques is enough for most experiments. This chapter gives an overview of some basics.
Sample Principle.Samples are the base for all knowledge. In everyday life, judgments and decisions rest on evidence from samples, directly or indirectly. A test is a sample of your knowledge and abilities, as with a statistics exam or a test for driver's license. Blood and urine samples can help diagnose your health. What others think of you depends on samples of your behavior.
Samples are equally important in psychological science. Nearly every experiment you read about in any of your textbooks presents evidence from a small sample of subjects, as with the infant monkeys in Harlow's “mother love” experiments. All those experiments you yourself are destined to do will also use small samples.
This fundamental role of samples appears in all sciences. The study of stars and galaxies depends on tiny samples of light. Our knowledge of dinosaurs comes from hard-won samples of scattered fossils; the same applies to our knowledge about hominid precursors of Homo sapiens.
Generalization from Samples. A sample is seldom important in its own right. Instead, we use evidence from the sample to reach some general conclusion. No one is interested in those particular infant monkeys studied in Harlow's mother love experiments. Similarly, the peas from Mendel's small monastery garden were thrown out long ago, whereas Mendel's inspired interpretation of the statistical pattern of these peas lives on in modern theory of genes.