Descriptive statistics: deals with methods of organizing, summarizing and presenting data in convenient and informative way (ie. graphing techniques) Use numerical techniques to summarize data; average. Inferential statistics: methods used to draw conclusions/inferences about characteristics of population based on sample data. Exit polls: random sample of votes exit the polling booth and asked for whom they voted; sample proportion of voters supported the candidates is computed. Population: group of all items of interest; very large; does not necessarily refer to group of people. Parameter: descriptive measure of a population; mean # of soft drinks consumer by all students at the university or proportion of 5 million who voted for bush. Sample: set of data drawn from the studied population. Statistic: descriptive measure of a sample; used to make inferences about parameters. Statistical inference: process of making an estimate/prediction/decision about a population based on sample data; measure of reliability. Confidence level: proportion of times that an estimating procedure will be correct.