Statistics and Data Analysis Process Section 1.3

Two Branches of Statistics Descriptive Statistics – includes methods for organizing and summarizing data Inferential Statistics – involves generalizing from a sample to the population from which it was selected and assessing the reliability of such generalizations

Sample vs. Population A building contractor has a chance to buy an odd lot of 5000 used bricks at an auction. She is interested in determining the proportion of bricks in the lot that are cracked and therefore unusable for her current project, but does hot have enough time to inspect all the bricks. Instead, she checks 100 bricks to determine whether each is cracked. Describe the population and sample for this problem.

Sample vs. Population The admissions director at a large college wished to determine why some applicants who were accepted for the call term failed to enroll. The director contacted 300 applicants to collect a data set. What is the population of interest? What group constitutes the sample?

The Data Analysis Process 1.Understanding the nature of the problem 2.Deciding what to measure and how to measure it 3.Data Collection 4.Data Summarization and preliminary analysis 5.Formal data analysis 6.Interpretation of results

Definitions Population – the entire collection of individuals or objects about which information is desired Sample – is a subset of the population, selected for study in some prescribed manner