ABSTRACT
The main purpose of inferential statistics is to estimate, as accurately as possible, information about a population of subjects by examining the characteristics of a subset of that population. Once a population has been defined, the next step is to select a subset of subjects to be included in the sample. The best way to be assured that a sample accurately represents a population is to use a procedure called random sampling. People often use the scientific method without really thinking about it. Consider the decision of whether or not to take an umbrella on people way to work. The estimation of a standard error is an important concept related to all statistical hypothesis testing. Any standard error can be used and generally interpreted in the same way that the standard deviation is used and interpreted. Confidence levels can be constructed to contain the parameter of interest with varying amounts of confidence.
