Section 1.2 Summary
- The field of statistics is the art and science of collecting, analyzing, presenting, and interpreting data.
- Descriptive statistics refers to methods for summarizing and organizing the information in a data set. Data sets include information collected on elements. Variables are characteristics of an element and can take different values for different elements.
- Variables may be either quantitative or qualitative. A qualitative variable may be classified into categories. A quantitative variable takes numeric values upon which arithmetical operations may meaningfully be performed. A discrete variable is a quantitative variable that can take either a finite or a countable number of possible values. A continuous variable is a quantitative variable that can take an infinite number of possible values.
- Data may be classified according to four levels of measurement: nominal, ordinal, interval, and ratio.
- A population is a collection of all elements of interest, whereas a sample is a subset of the population. The characteristics for a population are called parameters, whereas the characteristics for a sample are called statistics. Inferential statistics consists of methods for estimating and drawing conclusions about population characteristics based on the information in the sample.