2 11 - 2Chapter GoalsWhen you have completed this chapter, you will be able to:1.Explain what is meant by statistics.2.Identify the role of statistics in the development of knowledge and everyday life.3.Explain what is meant by descriptive statistics and inferential statistics.4.Distinguish between a qualitative variable and a quantitative variable.and...
3 11 - 3Chapter Goals5.Distinguish between a discrete variable and a continuous variable.6.Collect data from published and unpublished sources.7.Distinguish among the nominal, ordinal, interval, and ratio levels of measurement.8.Identify abuses of statistics.and...
4 11 - 4Chapter Goals9.Gain an overview of the art and science of statistics.We recommend that you read this chapter at least twice, once at the beginning and once at the end of your course!
5 Statistics? What is Meant by collecting organizing presenting data …it is the art and science of…collectingorganizingpresenting datadrawing inferences from a sample of information about an entire populationas well aspredicting and developing policy analysisWhat is MeantbyStatistics?
11 Methods of… collecting organizing presenting Types of StatisticsDescriptiveInferentialMethods of… collecting organizing presentingandanalyzing dataScience of… making inferences about a population, based on sample information.
12 Identify the following… C. Wine tasters sip a few drops of wine to make a decision with respect to all the wine waiting to be released for sale.A. A Gallup poll found that 83% of the people in a survey knew which country won the gold medal in Men’s Hockey in 2002.B. The accounting department of a firm will select a sample of invoices to check for accuracy of all the invoices of the company.DescriptiveInferential
13 The Method of Experimentation We start off with particular observations from the real world and draw conclusions about the general patterns in the real world!1. Define the experimental goal or a working hypothesis2. Design an experiment3. Collect data4. Estimate the values/relations5. Draw inferences6. Predict and prepare policy analysisChapters 8 and 12Chapters 3 and 4Chapters 5,7,8 and 9
14 Real World Real World The Method of Experimentation Deductive Method Inductive MethodRealWorldStatistical TechniquesDefinitions & AssumptionsExperimental Design & Data CollectionRules of LogicObjective or Working-HypothesisRealWorldImplications or Hypotheses
15 Let’s review the steps they would take to prepare the estimate. A StudyA study was undertaken to estimate the average height of penguins in Antarctica.Let’s review the steps they would take to prepare the estimate.
17 A population is a collection of all possible individuals, objects, or measurements of interest
18 POPULATION Say, 101 Sample POPULATION FromPOPULATIONSampleTake aSay, 101…which are deemed to be representative of thePOPULATIONWhat we now need is…
19 Raw Data 101 Sample Take a Measurement for each one in the sample Record
20 readable and understandable Goal?WhatNow…to put the datainto areadable and understandableformat!Displaying Data Results
21 Two methods that can be used to ‘see’ what the data conveys are Tables and Graphs/ChartsMore on these in chapter 2…
22 Tables e.g. 101 … are an efficient method of displaying data and depicting data accurately.e.g.101More on these in chapter 2…
23 Bar Pie Line Scatter Histogram Charts Graphs More on these in chapter 2…
24 Why take a sample instead of studying every member of the population? Costs of surveying the entire population may be too large or prohibitiveDestruction of elements during investigationAccuracy of resultsMore in chapter 8 …
25 Why Study Statistics?Data are everywhereStatistical techniques are used to make many decision that affect our livesNo matter what your future line of work, you will make decisions that involve data. An understanding of statistical methods will help you make these decisions more effectively.
27 a characteristic of a population or sample Types of DataA Variablea characteristic ofa population or samplethat is of interest to us
28 Types of Data Variables QualitativeQuantitativeCategoricalObservationsNumericalObservations
29 Variables Qualitative – or Attribute Female Country of Birth U.K. GermanyTaiwanChinaIndiaJapanRussiaEye ColourBlueBrownHazelGreenRedGenderMaleFemale
30 Variables Quantitative – Numeric Minutes to end of Class 5545305Number of Two-Door Garages in a Street10203040...Number of Satisfied Maple Leafs Fans203040…Number of Children in a Family1234…
31 … can be classified as either VariablesQuantitativeNumericalObservations… can be classified as eitherDiscrete orContinuousCharacteristics… can only assume certain values and there are usually “gaps” between valuesDiscretee.g. - Number of bedrooms in a house- Number of hammers sold (1,2,3,…etc)
32 Variables Continuous Quantitative … can be classified as either NumericalObservations… can be classified as eitherDiscrete orContinuousCharacteristics… can assume any value within a specified range!Continuouse.g. - Pressure in a tire- Weight of a pork chop- Height of students in a class
33 Summary of Types of Variables DataQualitativeCategoricalObservationsQuantitativeNumericalObservationsDiscreteContinuous(number of children)(time used for an exam)
35 Sources of Statistical Information Published DataStatistical AbstractsWeatherSports
36 Sources of Statistical Information Government of Canada & ProvincesInternet
37 Sources of Statistical Information InternationalOrganization for Economic Co-operation and DevelopmentIMF
38 Sources of Statistical Information Commissioned surveys:To develop information for the survey that they are doing, pollsters often contact the selected ‘sample population’.For Example…At home, over the telephone, by mail, by , in the street, and at shopping malls!How to collect data…
41 Candy By Colour only Levels of Measurement M & Ms Nominal Data can only be classified into categories or counted and cannot be arranged in any particular orderM & MsExampleCategory:CandyBy Colour onlyClassification:(No natural order)
42 Levels of Measurement M & Ms Nominal Mutually Exclusive: ExampleMutually Exclusive:…where an individual, object, or measurement is included in ONLY ONE CATEGORYExhaustive:…where each individual, object, or measurement MUST APPEAR in one of the categories
43 During a taste test of 4 soft drinks: Levels ofMeasurementOrdinal…involves data arranged in some order,but the differences between data values cannot be determined or are meaningless!ExampleDuring a taste test of 4 soft drinks:Mello Yello was ranked number……..…. 1.Sprite number……………………………. 2.Seven Up number..…………………..…... 3.Orange Crush number ….……………….4.
44 Levels of Measurement Interval There is no natural zero point …similar to the Ordinal Level, with the additional property that meaningful amounts of differences between data values can be determined.There is no natural zero pointExampleTemperature on the Celsius scale.
45 Distance travelled by manufacturer’s representatives per month Levels ofMeasurementRatio…the Interval Level with an inherent zero starting point.Differences and ratios are meaningful for this level of measurement.ExamplesMonthly income of surgeonsDistance travelled by manufacturer’s representatives per month
47 “There are three kinds of lies… Benjamin Disraeli said…“There are three kinds of lies…LiesDamned Lies&Objects: Stats_2ProbSample-B.ppt (Probability)Action Button: Stat Samples_B.ppt (Penguins) for Probabilitypen-heights_2Rev.xls (for Penguins)Statistics!
49 … graphs can also be misleading CautionAs you begin to study statistical methods, you are cautioned to take what you see published as “statistical facts” with a healthy grain of skepticism!… an average may not be representative of all the data… graphs can also be misleading… be sure to study the sampling methodsFor Example
50 CautionReview the following three slides and notice the effect that the different scales have on your interpretation of the pattern between Crime and Unemployment Rates.