STA 115 Study Guide - Midterm Guide: Pie Chart, Histogram, Confounding
Document Summary
Population: entire groups of individuals which we want info about. Sample: part of population from which we actually collect information and is used to draw conclusions as a whole. Observational study: surveying something without changing any variables, simply observing it, cannot determine cause and effect. Experiment: deliberately imposes some kind of treatment on individuals in order to observe their responses. Can determine cause and effect by manipulating variable. Sample survey: used to survey some groups of individuals by studying only some of its members because they represent a larger group. Biased: systematically favors a specific outcome, excludes certain segments of the population, always deviates in one direction. Convenience sampling: selection of whichever individuals are easiest to reach. Voluntary response sample: chooses itself by responding to general appeal; write-in or call-in opinion polls. People only answer these if they have very strong opinions.
