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

Introduction to Statistics2 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 Stats as a Discipline Type of Mathematics How different? Most important element?

Introduction to Statistics3 2 Dictionary Meanings for the Word ‘Statistics’ 1.A set of numerical facts 2The method used to collect, analyze, present, interpret and distill data to make intelligent decisions

Introduction to Statistics4 How Can Statistics Help Us? Stats help us make scientific and intelligent decisions, often called educated guesses about real life phenomena

Introduction to Statistics5 What happens without Statistics? Without stats we live in uncertainty with no precise solutions to real-life problems.

Introduction to Statistics6 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 Statistics7 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 Statistics8 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 Statistics9 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 Statistics10 Key Vocabulary Continued Here are three terms: Individual, Sample and Population. Generally speaking, in set theory terms, for a survey, individual  sample  population If however, all individuals = sample = population, then you have a census. Normal Survey Census Individual All Individuals=

Introduction to Statistics11 Good Data vs. Bad Data Good DataThe result of intelligent effort and good random sampling methods Bad DataThe result of laziness, lack of understanding, bad sampling technique or the desire to mislead others

Introduction to Statistics12 Applying Statistical Vocabulary--Example QuestionIs achievement at Washington High School different for males vs. females? SurveyWe 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 Statistics13 Applying Statistical Vocabulary—Cont’d PopulationBegin 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 SizeIf 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 Statistics14 Applying Statistical Vocabulary—Cont’d IndividualsRandomly select males by class and females by class in the school VariableWhat data will we collect? Decide on “What is your GPA?”-- as a measure of achievement DataCollect 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 DataThe unit of GPA is a number between zero and four in points.

Introduction to Statistics15 Applying Statistical Vocabulary—Cont’d AnalysisCompare 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 Possibilitiesmales and females 2) GPA’s are higher for males vs. females; 3) GPA’s arehigher for females vs. males ApplicabilityAre our conclusions true for the entire population of WHS? Or for all American high school students?

Introduction to Statistics16 Elements of a Survey 1What question is to be answered? 2Why specifically are we gathering the data? (What do we want to know?) 3What population is going to be used to answer the question? 4What sample of the population represents the whole? 5How is the sample chosen? 6Is the sample random?

Introduction to Statistics17 Elements of a Survey 7How 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? 9What are the units for each piece of data collected? 10Any question about the trustworthiness of the data?

Introduction to Statistics18 Elements of a Survey 11What 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 Statistics19 CW 100—Fast Food & USA Today

Introduction to Statistics20 Key Vocabulary in Statistics--Answers QuestionStatistical surveys usually begin with a general idea we want an answer for PopulationThe entire collection of individuals or objects about which information is desired SampleA subset of the population selected for a study by some specific criteria or in a prescribed manner

Introduction to Statistics21 Key Vocabulary Continued--Answers CensusA study using the entire population IndividualAn object which is one member of the sample. The member could be a person, animal or thing VariableAny characteristic of an individual. These characteristics take on different values for different individuals.

Introduction to Statistics22 Key Vocabulary Continued--Answers Survey A voluntary encounter between strangers, one the interviewer and the other the individual. InterviewerA person who seeks information from the respondent by engaging in a special type of conversation. DataNumbers collected in a particular context. During a survey, the interviewer collects this. Always has units. StatisticianThe person who analyzes, distills and interprets the data collected.

Introduction to Statistics23 Key Vocabulary Continued--Answers AnalysisTake the data. Crunch it. Interpret it in context. ApplicabilityTake the conclusions and decide if they apply to the sample only or to the larger population.

Introduction to Statistics24 The 4-Tardy Rule DON’T BE TARDY TO CLASS! On your 3 rd tardy to class during a semester I will remind you that you have reached my limit. On your 4 th 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...