Chapter 1 Nature of Probability and Statistics
OBJECTIVES
Demonstrate knowledge of statistical terms. Differentiate between the two branches of statistics. Identify types of data. Identify the measurement level for each variable. Identify the four basic sampling techniques. Explain the difference between an observational and an experimental study. Explain how statistics can be used and misused. Explain the importance of computers and calculators in statistics.
Statistics is the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data. Descriptive statistics consists of the collection, organization, summarization, and presentation of data. Inferential statistics consists of generalizing from samples to populations, performing estimations hypothesis testing, determining relationships among variables, and making predictions. (Probability, Hypothesis testing, relationships between variables, predictions) Probability is the chance of an event occurring. A population consists of all subjects that are being studied. A sample is a group of subjects selected from a population.
Variables and Types of Data
In order to gain knowledge about seemingly haphazard events, statisticians collect information for variables that describe the events. A variable is a characteristic or attribute that can assume different values. Data are the values that variables can assume. A data set is a collection of data values. Each value in the data set is called a data value or a datum. Random variables have values that are determined by chance.
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Chapter 1 Nature of Probability and Statistics
Qualitative variables can be placed into distinct categories according to some characteristic or attribute. Quantitative variables are numerical in nature and can be ordered or ranked. Quantitative variables can be further classified into two groups. o Discrete variables assume values that can be counted. o Continuous variables