What is Statistics? Why Study Statistics? Key Concepts of Statistics

1. What is Statistics?Why Study Statistics?Key Concepts of Statistics Introducing the Basic Words of the Survey

2. Stats as a Discipline Type of Mathematics How different? Most important element? What is the Discipline of Statistics? • The art and science of collecting, analyzing, presenting, interpreting and distilling data • Applied mathematics, different from all other math courses you’ve ever taken • It’s ‘chatty’math, imprecise and subject to interpretation. • Statistics is about common sense Introduction to Statistics

3. 2 Dictionary Meanings for the Word ‘Statistics’ • A set of numerical facts • 2 The method used to collect, analyze, present, interpret and distill data to make intelligent decisions Introduction to Statistics

4. How Can Statistics Help Us? Introduction to Statistics

5. What happens without Statistics? Introduction to Statistics

6. Key Vocabulary in Surveys • _______Statistical surveys usually begin with a general idea we want an answer for • _______The entire collection of individuals or objects about which information is desired • _______A subset of the population selected for a study by some specific criteria or in a prescribed manner. Usually chosen randomly. Introduction to Statistics

7. Key Vocabulary Continued • ________ A study using the entire population • ________ An object which is one member of the sample. The member could be a person, animal or thing • ________ Any characteristic of an individual. These characteristics take on different values for different individuals. Introduction to Statistics

8. Key Vocabulary Continued • _______ A voluntary encounter between strangers, one the interviewer and the other the individual. • _______ A person who seeks information from the individual by engaging in a special type of conversation. • ________ Numbers collected in a particular context. During a survey, the interviewer collects this. Almost always has units. • ________ The person who analyzes, distills and interprets the data collected. Introduction to Statistics

9. Key Vocabulary Continued • _________ Take the data. Crunch it. Interpret it in context. • _________ Take the conclusions and decide if they apply to the sample only or to the larger population. Introduction to Statistics

10. Key Vocabulary Continued Normal Survey • Here are three terms: Individual, Sample and Population. Generally speaking, in set theory terms, for a survey, individualÍ sample Í population If however, all individuals = sample = population, then you have a census. Census Individual All Individuals= Introduction to Statistics

11. Good Data vs. Bad Data Good Data The result of intelligent effort and good random sampling methods Bad Data The result of laziness, lack of understanding, bad sampling technique or the desire to mislead others Introduction to Statistics

12. Applying Statistical Vocabulary--Example • Question Is achievement at Washington High School different for males vs. females? • Survey We want to know if Washington HS gender population has different achievement, so we design a survey to answer the question. Why gather the data? Introduction to Statistics

13. Applying Statistical Vocabulary—Cont’d • Population Begin by using WHS as our population to study • Pop vs. Sample Do we have to use the whole population of WHS or can we sample them? • Sample Size If a sample, then how many individuals should we choose & how should we choose them? We decide on 200 students, 100 males and 100 females, 50 from each of the freshmen, sophomores, juniors and seniors. • How to Sample? We will RANDOMLY choose individuals in each category Introduction to Statistics

14. Applying Statistical Vocabulary—Cont’d • Individuals Randomly select 25-25-25-25 males by class and 25-25-25-25 females by class in the school • Variable What data will we collect? Decide on “What is your GPA?”-- as a measure of achievement • Data Collect it by interview or by looking at ‘office data.’ Collect GPA numbers for our 4 levels of males vs. 4 levels of females. • Units of Data The unit of GPA is a number between zero and four in points. Introduction to Statistics

15. Applying Statistical Vocabulary—Cont’d • Analysis Compare the ‘average’ GPA’s for males vs. females for each grade level at WHS, using our collected data. Compare overall GPA’s, too. • Conclusion 1) GPA’s are the similar for Possibilities males and females 2) GPA’s are higher for males vs. females; 3) GPA’s are higher for females vs. males • Applicability Are our conclusions true for the entire population of WHS? Or for all American high school students? Introduction to Statistics

16. Elements of a Survey • What question is to be answered? • Why specifically are we gathering the data? (What do we want to know?) • What population is going to be used to answer the question? • What sample of the population represents the whole? • How is the sample chosen? • Is the sample random? Introduction to Statistics

17. Elements of a Survey 7 How many individuals in the sample are chosen and in what units? 8 What is the variable to be measured and what data represents that variable? 9 What are the units for each piece of data collected? 10 Any question about the trustworthiness of the data? Introduction to Statistics

18. Elements of a Survey 11 What are some general conclusions to be drawn about the results? 12 Can we apply the conclusions to the entire population? Can we apply the conclusion beyond the population? Introduction to Statistics

19. CW 100—Fast Food & USA Today Introduction to Statistics

20. Key Vocabulary in Statistics--Answers • Question Statistical surveys usually begin with a general idea we want an answer for • Population The entire collection of individuals or objects about which information is desired • Sample A subset of the population selected for a study by some specific criteria or in a prescribed manner Introduction to Statistics

21. Key Vocabulary Continued--Answers • Census A study using the entire population • Individual An object which is one member of the sample. The member could be a person, animal or thing • Variable Any characteristic of an individual. These characteristics take on different values for different individuals. Introduction to Statistics

22. Key Vocabulary Continued--Answers • Survey A voluntary encounter between strangers, one the interviewer and the other the individual. • Interviewer A person who seeks information from the respondent by engaging in a special type of conversation. • Data Numbers collected in a particular context. During a survey, the interviewer collects this. Always has units. • Statistician The person who analyzes, distills and interprets the data collected. Introduction to Statistics

23. Key Vocabulary Continued--Answers • Analysis Take the data. Crunch it. Interpret it in context. • Applicability Take the conclusions and decide if they apply to the sample only or to the larger population. Introduction to Statistics

24. The 4-Tardy Rule DON’T BE TARDY TO CLASS! • On your 3rd tardy to class during a semester I will remind you that you have reached my limit. • On your 4th tardy to class, I will deduct 2 points from your next test. • On each succeeding tardy after that, you will also lose another 2 points. • Lost points can make a HUGE difference in your grade. . . Introduction to Statistics