Chapter 1 - What is statistics? When you have completed this chapter, you will be able to: Explain what is meant by statistics, identify the role of statistics in the development of knowledge and everyday life, explain what is meant by descriptive statistics and inferential statistics, distinguish between a qualitative variable and a quantitative variable,...
1 1 What is Statistics? Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 2 When you have completed this chapter, you will be able to: Explain what is meant by statistics Identify the role of statistics in the development of knowledge and everyday life Explain what is meant by descriptive statistics Distinguish between a qualitative variable and a quantitative variable and inferential statistics Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 3 Distinguish between a discrete variable and a continuous variable Collect data from published and unpublished sources Distinguish among the nominal, ordinal, interval, and ratio levels of measurement Identify abuses of statistics Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 4 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! Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 5 …it is the art and science of… collecting What What is is Meant Meant by by Statistics? Statistics? Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. organizing presenting data drawing inferences from a sample of information about an entire population as well as predicting and developing policy analysis 1 6 in everyday life Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Who uses Statistics? Statistics? Who uses 1 7 Those using Statistical techniques include : Marketers Marketers Economists Economists Sports people Sports people Consumers Consumers Statisticians Statisticians Quality Controllers Quality Controllers Politicians Physicians Politicians Physicians Accountants Accountants Hospitals Hospitals Educators Educators Investors Investors Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Who uses Statistics? Statistics? Who uses Weather Forecasters Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 8 Who uses Statistics? Statistics? Who uses Sports Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 9 1 10 Types of Statistics Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 41 Nominal Data can only be classified into categories or counted Data can only be classified into categories or counted and cannot be arranged in any particular order and cannot be arranged in any particular order Example Example M & Ms Category: Category: Candy Classification: Classification: By Colour only Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. (No natural order) 1 42 Nominal Example Example M & Ms Mutually Exclusive: Mutually Exclusive: …where an individual, object, or measurement is included in ONLY ONE CATEGORY Exhaustive: Exhaustive: …where each individual, object, or measurement MUST APPEAR in one of the categories Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 43 Ordinal …involves data arranged in some order, but the differences between data values cannot be determined or are meaningless! Example Example During a taste test of 4 soft drinks: Mello Yello was ranked number…… …. 1. Sprite number……………………………. 2. Seven Up number ………………… … 3 Orange Crush number ….……………….4 Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 44 Interval …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 point Example Example Temperature on the Celsius scale Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 45 Ratio …the Interval Level with an inherent zero starting point. Differences and ratios are meaningful for this level of measurement Examples Examples Monthly income of surgeons Distance travelled by manufacturer’s representatives per month Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 46 Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Benjamin Disraeli said… Benjamin Disraeli said… 1 47 “There are three kinds of lies… “There are three kinds of lies… Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 48 Figures don’t lie Liars figure! Caution Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Caution 1 49 As you begin to study statistical methods, As you begin to study statistical methods, you are cautioned to take what you see you are cautioned to take what you see published as “statistical facts” published as “statistical facts” with a healthy grain of with a healthy grain of skepticism! skepticism! … an average may not be representative of all the data … an average may not be representative of all the data … graphs can also be misleading … graphs can also be misleading … be sure to study the sampling methods … be sure to study the sampling methods For Example Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Caution 1 50 Review the following three slides and notice the effect that the different scales have on your interpretation of the pattern between Crime and Unemployment Rates Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 51 Crime Rate (in thousands) Chart 111A Chart 111A 1986 1999 3200 3000 2800 2600 2400 2200 2000 0 1 2 3 4 5 6 7 8 9 10 11 12 Unemployment Rate (%) Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 52 Crime Rate (in thousands) Chart 111B Chart 111B 1986 1999 3000 2500 2000 1500 1000 500 500 0 7 8 9 10 11 12 Unemployment Rate (%) Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 53 Crime Rate (in thousands) Chart 111C Chart 111C 1986 1999 3200 3000 2800 2600 2400 2200 2000 7 8 9 10 11 12 Unemployment Rate (%) Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Test your learning… … Test your learning … … n o n o k ilcick CCl www.mcgrawhill.ca/college/lind Online Learning Centre for quizzes extra content data sets searchable glossary access to Statistics Canada’s EStat data …and much more! Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. 1 54 1 55 This completes Chapter 1 Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. ... 1 3 Distinguish between a discrete variable and a continuous variable Collect data from published and unpublished sources Distinguish among the nominal, ordinal, interval, and ratio levels of measurement... completed this chapter, you will be able to: Explain what is meant by statistics Identify the role of statistics in the development of knowledge and everyday life Explain what is meant by descriptive statistics ... as well as predicting and developing policy analysis 1 6 in everyday life Copyright © 2004 by The McGrawHill Companies, Inc. All rights reserved. Who uses Statistics? Statistics? Who uses