STT 212 Midterm: Exam One Study Guide

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Process of statistical analysis: identify the population: choose a sample representative of the population & collect data, exploratory data analysis (i. e. graphical displays/numerical summaries, use probability to identify how the sample may differ from the population inference. Experiment a planned intervention conducted to observe how a response variable behaves when one or more explanatory variables are manipulated. Goal: determine the effect of an explanatory variable on a response variable. Cause/effect conclusions can be drawn from experiments. Observational study observes the characteristics of the members of a population. Cause/effect conclusions cannot be drawn from observational studies due to confounding (when the effects of two variables on a response variable cannot be distinguished) Example: survey subjects randomly selected from within each class year strata non-overlapping groups that each have a common attribute among their units. Advantage over srs: fewer individuals are surveyed but the same information is obtained, guarantees representation of each stratum.