Читать книгу Interpreting and Using Statistics in Psychological Research - Andrew N. Christopher - Страница 27

We discussed the notions of population and sample previously in this chapter. We will expand on them here. Recall that a population is the entire group of people we want to learn about, and a sample is a subset of people drawn from that population that is intended to represent the characteristics of its population. In research, the purpose of the sample is to learn about characteristics of the population. As we said, when we say “characteristics of the population,” we are talking about variables, which again, are qualities that have different values or change among individuals.

As we discussed in this chapter, in most walks of life, we must operate with information about a sample from our personal experiences, and that can be problematic when drawing conclusions about the world. Variables, typically expressed quantitatively, that describe a population are called parameters. An example of a parameter would be the odds of dying in a terrorist attack and the odds of dying from a fall at home. However, we rarely, if ever, know and use parameters in our daily thinking. Rather, we rely on samples. This can be a problem when our goal is to be objective. When we want to be objective, we need some help. Therefore, we make use of statistics, which are accepted quantitative procedures that allow us to organize, summarize, and interpret information (called data) to draw conclusions about the world (i.e., the population). At this point and throughout the remainder of the book, we want to learn how to interpret and use statistics correctly.

P for Population, P for Parameter

S for Sample, S for Statistic

A nice heuristic to remember these concepts

Parameter: number that expresses a value in the population.

Statistic: number that expresses a value in the sample.