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STOR 155 Introductory Statistics

The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL. STOR 155 Introductory Statistics. Lecture 1: Overview. Registration Issues. Contact Charlotte Rogers : Hanes 321, 962-2307, crogers@email.unc.edu Fill out some paperwork with her to be put on the waiting list.

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STOR 155 Introductory Statistics

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  1. The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL STOR 155 Introductory Statistics Lecture 1: Overview Lecture 1

  2. Registration Issues • Contact Charlotte Rogers: Hanes 321, 962-2307, crogers@email.unc.edu • Fill out some paperwork with her to be put on the waiting list. Lecture 1

  3. My Strategy for Success • Stay active/involved in class. • Ask questions during class (especially if you do not understand something). • Do not feel shy or stupid. • Answer questions to help other students if you can. • Keep pace with the lectures, review daily, do homework after each lecture to help understand the materials. • Make effective use of office hours (Instructor and IA) and open tutorial sessions • Help you to answer questions about homework and lectures • Private time vs. public time Lecture 1

  4. What is Statistics? • "Data! Data! Data!" he cried impatiently. "I can't make bricks without clay." ----Sherlock Holmes The Adventures of the Copper Beeches • "Data! Data! Data!" he yelled loudly. "I can't teach Statistics without Data." ----Instructor Introductory Statistics Lecture 1

  5. Population Inference about population (using statistical tools) Sample of data What is Statistics? • Statistics: the science of collecting, organizing, and interpreting data. • data = information Lecture 1

  6. How can Statistics help us? • claims that it contains 1000 chips.Is this true? • Among a group of randomly chosen people, how likely is it for two of them to have the same birthday? • What is the relationship between Income and Years of Education? • Design your own experiment, collect data, analyze data and draw conclusions. Lecture 1

  7. SAT Scores • Parents and teachers have been concerned about the trend of declining SAT scores and sought ways to halt the decline. • One question: the effect of classroom atmosphere (strict or liberal). • To answer the question, 50 students (24 males and 26 females) participated in a study on student performance, as measured by SAT scores at the end of the school year. • The students were divided into two groups of 25 each (12 males and 13 females), with Group 1 to study under a strict atmosphere while Group 2 under a very permissive atmosphere. • They were matched according to socio-economic background. Lecture 1

  8. SAT Scores • After nine months, all students were given the same standardized tests: the verbal test and the mathematics test. Lecture 1

  9. SAT Scores • This example involves data collection, data analysis,andstatistical inference. • How? • Questions: • Does stricter classroom atmosphere increase the average score? • Why “matched according to socio-economic background”? • Why “12 males and 13 females per group”? • Is the group size 50 large enough to make a confident conclusion? Lecture 1

  10. Fundamental Concepts • Population: the entire group of individuals that we want information about. • Students (who are about to take SAT) • Sample: a part of the population that we actually examine in order to gather information. • those students selected into the study • Sample size: number of observations/individuals in a sample. • 50 • Statistical inference: to make an inference about a population based on the information contained in a sample. • Based on the data from the study, to infer whether a stricter classroom atmosphere increases SAT scores in general. Lecture 1

  11. Fundamental Concepts • A parameter is a value that describes the population. It’s fixed but unknown in practice. • the average SAT score of all the students, who are about to take SAT. • A statistic is a value that describes a sample. It’s known once a sample is obtained. • the average SAT score of all the students, who are selected into the study. • asample analogy of the parameter. Lecture 1

  12. Practice Exercise • Suppose you are interested in finding out the average SAT score of UNC unders, • The SAT scores of all UNC unders in STOR155 • The SAT scores of all UNC unders • Suppose you are interested in finding out the average SAT score of US unders, • The SAT scores of all UNC unders • The SAT scores of all US unders Lecture 1

  13. Take Home Message • Statistics is the science of data: • Collecting • Analyzing • Decision making = Information processing • Fundamental concepts: • Population, parameter,sample, statistic, sample size • You can do a LOT with statistics … what ? Lecture 1

  14. Take home message • Interested in population, but it’s too large to become known completely • Statisticians work on sample, which is a smaller and observable ``proxy’’ • There is uncertainty in this transition, hence errors are inevitable … • That’s why statistical methods are needed … Lecture 1

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