STAT 2040 Lecture Notes - Lecture 2: Confounding, Categorical Variable, Dependent And Independent Variables
1 Apr 2015
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Document Summary
The population is the set of all individuals or units of interest to an investigator. A parameter is a numerical characteristic of a population. In practice it is usually impractical or impossible to take measurements on the entire population, and thus we typically do not know the values of parameters. A sample is a subset of individuals or units selected from the population. A statistic is a numerical characteristic of a sample. Types of sampling: simple random sampling, every possible sample of size n has the same chance of being selected. stratified random sampling cluster sampling. In a randomized experiment the researchers apply different conditions (different diets, different drugs, or different teaching methods, for example) to experimental units that have been randomly assigned to different groups. In an observational study (as opposed to an experiment), researchers observe and measure variables, but do not impose any conditions. Well-designed experiments can give strong evidence of a cause-and- effect relationship.
