Important Terms Major Branches of Statistics 1. Descriptive Statistics – – – Organizing, Summarizing Information Graphical techniques Numerical techniques 2. Inferential Statistics – – Estimation Decision making © 2008 Brooks/Cole, a division of Thomson Learning, Inc. Important Terms Sample – A sample is a subset of the population, selected for study in some prescribed manner. Using sample data rather than population data is – more practical than a census. – Gives variable results with some possibility of a wrong conclusion being adopted. © 2008 Brooks/Cole, a division of Thomson Learning, Inc. Practice Problem The financial aid officers of a university wish to estimate the average amount of money that students spend on textbooks each term. They select 150 students and ask them the amount spent on book. Describe the population and sample for this problem. Population – The entire collection of individuals or objects about which information is desired is called the population. Collection of data from every member of the population is called a census, – allows a question about the population to be definitively answered. – may be expensive, impractical, or sometimes impossible. © 2008 Brooks/Cole, a division of Thomson Learning, Inc. Practice Problem Mr. Holland wants to get the opinions of graduating seniors from last year (412 students). He sends a survey to 100 of the graduating seniors, and 43 reply. Identify the population and sample.