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Agresti/Franklin Statistics, 1 of 33 Enrollment Fall 2005 (all students) ClassificationMenWomenTotal Undergraduate 1,533 (52%) 1,416 (48%) 2,949 Professional*172239 Graduate1,2856981,983 Master505276781 Doctoral7804221,202 Total 2 2,835 2,136 4,971
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Agresti/Franklin Statistics, 2 of 33 Geographic Origin 3 (Fall 2005) Undergraduates*GraduatesTotal MasterDoctoral Texas 1,532 (51.3%) 4744822,488 Other U.S. 1,320 (44.2%) 1571781,655 International 96 (3.2%) 123521740 Not Designated 40 (1.3%) 272188 Total2,9887811,2024,971
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Agresti/Franklin Statistics, 3 of 33 Student Demographics (Fall 2005) UndergradGrad #%Master%Doctoral% Architecture1264%749%11% Engineering75125%365%46439% Humanities55919%162%17514% Management--0%47160%--0% Music1284%12316%393% Natural Sciences70423%294%34629% Social Sciences69323%--0%13511% Interdisciplinary211%--0%423% Continuing Studies--0%324%--0% Unclassified61%--0%--0% Total2,9887811,202100%
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Agresti/Franklin Statistics, 4 of 33 Chapter 1 Statistics: The Art and Science of Learning from Data Learn …. What Statistics Is Why Statistics Is Important
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Agresti/Franklin Statistics, 5 of 33 Chapter 1 Learn… How Data is Collected How Data is Used to Make Predictions
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Agresti/Franklin Statistics, 6 of 33 Section 1.1 How Can You Investigate using Data?
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Agresti/Franklin Statistics, 7 of 33 Health Study Does a low-carbohydrate diet result in significant weight loss?
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Agresti/Franklin Statistics, 8 of 33 Market Analysis Are people more likely to stop at a Starbucks if they’ve seen a recent TV advertisement for their coffee?
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Agresti/Franklin Statistics, 9 of 33 Heart Health Does regular aspirin intake reduce deaths from heart attacks?
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Agresti/Franklin Statistics, 10 of 33 Cancer Research Are smokers more likely than non- smokers to develop lung cancer?
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Agresti/Franklin Statistics, 11 of 33 To search for answers to these questions, we… Design experiments Conduct surveys Gather data
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Agresti/Franklin Statistics, 12 of 33 Statistics is the art and science of: Designing studies Analyzing data Translating data into knowledge and understanding of the world
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Agresti/Franklin Statistics, 13 of 33 Example from the National Opinion Center at the University of Chicago: General Social Survey (GSS) provides data about the American public Survey of about 2000 adult Americans
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Agresti/Franklin Statistics, 14 of 33 Example from GSS: Do you believe in life after death?
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Agresti/Franklin Statistics, 15 of 33 Three Main Aspects of Statistics Design Description Inference
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Agresti/Franklin Statistics, 16 of 33 Design How to conduct the experiment How to select the people for the survey
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Agresti/Franklin Statistics, 17 of 33 Description Summarize the raw data Present the data in a useful format
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Agresti/Franklin Statistics, 18 of 33 Inference Make decisions or predictions based on the data.
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Agresti/Franklin Statistics, 19 of 33 Example: Harvard Medical School study of Aspirin and Heart attacks Study participants were divided into two groups Group 1: assigned to take aspirin Group 2: assigned to take a placebo
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Agresti/Franklin Statistics, 20 of 33 Example: Harvard Medical School study of Aspirin and Heart attacks Results: the percentage of each group that had heart attacks during the study: 0.9% for those taking aspirin 1.7% for those taking placebo
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Agresti/Franklin Statistics, 21 of 33 Example: Harvard Medical School study of Aspirin and Heart attacks Can you conclude that it is beneficial for people to take aspiring regularly? Example: Harvard Medical School study of Aspirin and Heart attacks
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Agresti/Franklin Statistics, 22 of 33 Section 1.2 We Learn About Populations Using Samples
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Agresti/Franklin Statistics, 23 of 33 Subjects The entities that we measure in a study Subjects could be individuals, schools, countries, days,…
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Agresti/Franklin Statistics, 24 of 33 Population and Sample Population: All subjects of interest Sample: Subset of the population for whom we have data
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Agresti/Franklin Statistics, 25 of 33 Geographic Origin (Fall 2005) Undergraduates*GraduatesTotal MasterDoctoral Texas 1,532 (51.3%) 4744822,488 Other U.S. 1,320 (44.2%) 1571781,655 International 96 (3.2%) 123521740 Not Designated 40 (1.3%) 272188 Total2,9887811,2024,971
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Agresti/Franklin Statistics, 26 of 33 Enrollment Fall 2005 ClassificationMenWomenTotal Undergraduate 1,533 (52%) 1,416 (48%) 2,949 Professional*172239 Graduate1,2856981,983 Master505276781 Doctoral7804221,202 Total 2 2,835 2,136 4,971
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Agresti/Franklin Statistics, 27 of 33 Majors (Fall 2005) UndergradGrad #%Master%Doctoral% Architecture1264%749%11% Engineering75125%365%46439% Humanities55919%162%17514% Management--0%47160%--0% Music1284%12316%393% Natural Sciences70423%294%34629% Social Sciences69323%--0%13511% Interdisciplinary211%--0%423% Continuing Studies --0%324%--0% Unclassified61%--0%--0% Total2,9887811,202100%
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Agresti/Franklin Statistics, 28 of 33 Example Format Picture the Scenario Question to Explore Think it Through Insight Practice the concept
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Agresti/Franklin Statistics, 29 of 33 Example: The Sample and the Population for an Exit Poll In California in 2003, a special election was held to consider whether Governor Gray Davis should be recalled from office. An exit poll sampled 3160 of the 8 million people who voted.
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Agresti/Franklin Statistics, 30 of 33 What’s the sample and the population for this exit poll? The population was the 8 million people who voted in the election. The sample was the 3160 voters who were interviewed in the exit poll. Example: The Sample and the Population for an Exit Poll
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Agresti/Franklin Statistics, 31 of 33 Descriptive Statistics Methods for summarizing data Summaries usually consist of graphs and numerical summaries of the data
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Agresti/Franklin Statistics, 32 of 33 Types of U.S. Households
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Agresti/Franklin Statistics, 33 of 33 Inference Methods of making decisions or predictions about a populations based on sample information.
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Agresti/Franklin Statistics, 34 of 33 Parameter and Statistic A parameter is a numerical summary of the population A statistic is a numerical summary of a sample taken from the population
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Agresti/Franklin Statistics, 35 of 33 Randomness Simple Random Sampling: each subject in the population has the same chance of being included in that sample Randomness is crucial to experimentation
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Agresti/Franklin Statistics, 36 of 33 Variability Measurements vary from person to person Measurements vary from sample to sample
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Agresti/Franklin Statistics, 37 of 33 a. To describe whether a sample has more females or males. b. To reduce a data file to easily understood summaries. c. To make predictions about populations using sample data. d. To predict the sample data we will get when we know the population. Inferential Statistics are used:
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Agresti/Franklin Statistics, 38 of 33 Chapter 2 Exploring Data with Graphs and Numerical Summaries Learn …. The Different Types of Data The Use of Graphs to Describe Data The Numerical Methods of Summarizing Data
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Agresti/Franklin Statistics, 39 of 33 Section 2.1 What are the Types of Data?
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Agresti/Franklin Statistics, 40 of 33 In Every Statistical Study: Questions are posed Characteristics are observed
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Agresti/Franklin Statistics, 41 of 33 Characteristics are Variables A Variable is any characteristic that is recorded for subjects in the study
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Agresti/Franklin Statistics, 42 of 33 Variation in Data The terminology variable highlights the fact that data values vary.
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Agresti/Franklin Statistics, 43 of 33 Example: Students in a Statistics Class Variables: Age GPA Major Smoking Status …
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Agresti/Franklin Statistics, 44 of 33 Data values are called observations Each observation can be: Quantitative Categorical
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Agresti/Franklin Statistics, 45 of 33 Categorical Variable Each observation belongs to one of a set of categories Examples: Gender (Male or Female) Religious Affiliation (Catholic, Jewish, …) Place of residence (Apt, Condo, …) Belief in Life After Death (Yes or No)
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Agresti/Franklin Statistics, 46 of 33 Quantitative Variable Observations take numerical values Examples: Age Number of siblings Annual Income Number of years of education completed
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Agresti/Franklin Statistics, 47 of 33 Graphs and Numerical Summaries Describe the main features of a variable For Quantitative variables: key features are center and spread For Categorical variables: key feature is the percentage in each of the categories
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Agresti/Franklin Statistics, 48 of 33 Quantitative Variables Discrete Quantitative Variables and Continuous Quantitative Variables
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Agresti/Franklin Statistics, 49 of 33 Discrete A quantitative variable is discrete if its possible values form a set of separate numbers such as 0, 1, 2, 3, …
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Agresti/Franklin Statistics, 50 of 33 Examples of discrete variables Number of pets in a household Number of children in a family Number of foreign languages spoken
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Agresti/Franklin Statistics, 51 of 33 Continuous A quantitative variable is continuous if its possible values form an interval
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Agresti/Franklin Statistics, 52 of 33 Examples of Continuous Variables Height Weight Age Amount of time it takes to complete an assignment
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Agresti/Franklin Statistics, 53 of 33 Frequency Table A method of organizing data Lists all possible values for a variable along with the number of observations for each value
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Agresti/Franklin Statistics, 54 of 33 Example: Shark Attacks
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Agresti/Franklin Statistics, 55 of 33 Example: Shark Attacks What is the variable? Is it categorical or quantitative? How is the proportion for Florida calculated? How is the % for Florida calculated? Example: Shark Attacks
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Agresti/Franklin Statistics, 56 of 33 Insights – what the data tells us about shark attacks Example: Shark Attacks
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Agresti/Franklin Statistics, 57 of 33 Identify the following variable as categorical or quantitative: Choice of diet (vegetarian or non-vegetarian): a. Categorical b. Quantitative
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Agresti/Franklin Statistics, 58 of 33 Number of people you have known who have been elected to political office: a. Categorical b. Quantitative Identify the following variable as categorical or quantitative:
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Agresti/Franklin Statistics, 59 of 33 Identify the following variable as discrete or continuous: The number of people in line at a box office to purchase theater tickets: a. Continuous b. Discrete
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Agresti/Franklin Statistics, 60 of 33 The weight of a dog: a. Continuous b. Discrete Identify the following variable as discrete or continuous:
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Agresti/Franklin Statistics, 61 of 33 Section 2.2 How Can We Describe Data Using Graphical Summaries?
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Agresti/Franklin Statistics, 62 of 33 Graphs for Categorical Data Pie Chart: A circle having a “slice of pie” for each category Bar Graph: A graph that displays a vertical bar for each category
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Agresti/Franklin Statistics, 63 of 33 Example: Sources of Electricity Use in the U.S. and Canada
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Agresti/Franklin Statistics, 64 of 33 Pie Chart
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Agresti/Franklin Statistics, 65 of 33 Bar Chart
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Agresti/Franklin Statistics, 66 of 33 Pie Chart vs. Bar Chart Which graph do you prefer? Why?
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Agresti/Franklin Statistics, 67 of 33 Graphs for Quantitative Data Dot Plot: shows a dot for each observation Stem-and-Leaf Plot: portrays the individual observations Histogram: uses bars to portray the data
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Agresti/Franklin Statistics, 68 of 33 Example: Sodium and Sugar Amounts in Cereals
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Agresti/Franklin Statistics, 69 of 33 Dotplot for Sodium in Cereals Sodium Data: 0 210 260 125 220 290 210 140 220 200 125 170 250 150 170 70 230 200 290 180
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Agresti/Franklin Statistics, 70 of 33 Stem-and-Leaf Plot for Sodium in Cereal Sodium Data: 0 210 260 125 220 290 210 140 220 200 125 170 250 150 170 70 230 200 290 180
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Agresti/Franklin Statistics, 71 of 33 Frequency Table Sodium Data: 0 210 260 125 220 290 210 140 220 200 125 170 250 150 170 70 230 200 290 180
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Agresti/Franklin Statistics, 72 of 33 Histogram for Sodium in Cereals
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Agresti/Franklin Statistics, 73 of 33 Which Graph? Dot-plot and stem-and-leaf plot: More useful for small data sets Data values are retained Histogram More useful for large data sets Most compact display More flexibility in defining intervals
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Agresti/Franklin Statistics, 74 of 33 Shape of a Distribution Overall pattern Clusters? Outliers? Symmetric? Skewed? Unimodal? Bimodal?
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Agresti/Franklin Statistics, 75 of 33 Symmetric or Skewed ?
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Agresti/Franklin Statistics, 76 of 33 Example: Hours of TV Watching
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Agresti/Franklin Statistics, 77 of 33 Identify the minimum and maximum sugar values: a. 2 and 14 b. 1 and 3 c. 1 and 15 d. 0 and 16
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Agresti/Franklin Statistics, 78 of 33 Consider a data set containing IQ scores for the general public: What shape would you expect a histogram of this data set to have? a. Symmetric b. Skewed to the left c. Skewed to the right d. Bimodal
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Agresti/Franklin Statistics, 79 of 33 Consider a data set of the scores of students on a very easy exam in which most score very well but a few score very poorly: What shape would you expect a histogram of this data set to have? a. Symmetric b. Skewed to the left c. Skewed to the right d. Bimodal
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