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Unformatted text preview: STATISTICS 321 – Dr. Soma Roy Chapter 1: Sampling and Descriptive Statistics Consider the following • Hyundai wants to know what features of its Elantra model it should alter, so that amount of damage caused in a crash may be very small. What should they do? • The FDA wants to test a newly developed drug before it can be released in the market. • A newspaper company wants to start an online edition of its newspaper, but it will do so only if more than 25% of its current subscribers express an interest in subscribing to the online edition. • We want to know the average amount of money Cal Poly students spend on textbooks every quarter. Big Question : How do statisticians come into picture? Statisticians use to help you answer these and many other questions, and make informed decisions! Note : datum = singular, and data = plural. Statistics : What is/are Statistics? • Statistics is a discipline, and • the word statistics is the plural of statistic – a statistic is a number measured for some purpose. Statistics – as a discipline • Statistics is a collection of procedures and principles for gaining and analyzing information in order to help people make decisions when faced with uncertainty. Thus, for any experiment/survey/study we do the following 1 Sampling Consider this very common situation. Say, we expect some friends for dinner, and are eager to show off how well we can prepare tomato soup. We make a whole potful, and are waiting for our guests, when we are stricken by a great fear – what if the salt isn’t right? what if the pepper isn’t right? what if it doesn’t taste good? What do we do? Generally, when conducting any kind of statistical study, our interest in lies in a large group – this large group of interest is called a . Sometimes, it is easy to collect data on the entire population. Suppose, we want to find out the average height of students in this class – it’s easy to measure the height of 35 students, right? This is called a – collecting information on the entire population. What if we wanted to find out the average height of all students in the Cal State system – it wouldn’t be as easy anymore, right? More often than not, it is rather difficult to observe or collect data on the entire population. In such cases, we select ....
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