# The Measurement of Adolescents

## An Introduction to Statistical Thinking

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## Introduction

In the first section we work with only the full set of values being considered. The full set of values is called the population. Since it is not always possible or practical to study an entire population, we must use samples. Samples are subsets of the population. Selecting samples is one of the most important tasks of statistics because from the samples chosen inferences are made about the entire population. The reliability of the inferences depends in large part on the reliability of the sample.

Not all samples are useful. If we want reliable information about a population, the sample we choose must be representative of the entire population. The sample we want is called a random sample which means that every member of the population has an equal chance at being picked. The primary objective of Section II: Random Sample is to introduce the idea of randomness and to solve random sample problems.

Section III: Probability has as its objective to use the traditional definition of probability in finding probabilities and comparing experimental and theoretical probabilities. No matter how much information we acquire, we almost never know everything there is to know about any given situation. However, since decisions must be made, we guess-sometimes using only intuition and sometimes partial information. The more information, the more reliable the guess. Probability helps us put a numerical measure on the uncertainty of an event, on the risk we’re taking.

I consider Section I to be the most important part because it allows students to not only begin at the beginning of statistical work by gathering data, but it allows them also to be the generators of it. I am looking forward to the discussions in class as we evaluate the four week records.