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M ARIO F . T RIOLA

S TATISTICS. E LEMENTARY. Section 1-3 Uses and Abuses of Statistics. M ARIO F . T RIOLA. E IGHTH. E DITION. Almost all fields of study benefit from the application of statistical methods. Uses of Statistics. There are three kinds of lies: lies, damned lies, and statistics.

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M ARIO F . T RIOLA

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  1. STATISTICS ELEMENTARY Section 1-3 Uses and Abuses of Statistics MARIO F. TRIOLA EIGHTH EDITION

  2. Almost all fields of study benefit from the application of statistical methods Uses of Statistics

  3. There are three kinds of lies: lies, damned lies, and statistics. Benjamin Disraeli There are two kinds of statistics: the kind you look up and the kind you make up. Rex Stout First get your facts. Then you can distort them at your leisure. Mark Twain I gather, young man, that you wish to be a Member of Parliament. The first lesson that you must learn is, when I call for statistics about the rate of infant mortality, what I want is proof that fewer babies died when I was Prime Minister than when anyone else was Prime Minister. That is a political statistic. Winston Churchill

  4. Statistics in the hands of an engineer are like a lamppost to a drunk -- they're used more for support than illumination. A. E. Housman Numbers are like people; torture them enough and they'll tell you anything. Anonymous 78% of all statistics are made up on the spot. Anonymous It is easy to lie with statistics, but it is easier to lie without them. Frederick Mosteller

  5. Bad Samples Abuses of Statistics

  6. LiteraryDigestPoll of 1936 • Republican ALF LANDON running against incumbent Democrat FRANKLIN DELANO ROOSEVELT. • Literary Digest predicted LANDON would win in a landslide! • Had correctly predicted the winner of every presidential election since 1916. • Based prediction on responses from 2.3 million people. • Were • FDR won in a landslide! 1936 Franklin Delano Roosevelt WRONG!

  7. LiteraryDigestPoll of 1936 What Went Wrong? 1936 • Sent postcards to people with telephones, magazine subscribers, car owners, and a few people on lists of registered voters. • Sent out 10 million postcards but received only 2.3 million replies. • People who want a change were more likely to reply than those who were satisfied with the status quo. Biased Sample Franklin Delano Roosevelt Low Response Rate Self-Selected Survey

  8. self-selected survey (or voluntary response sample) one in which the respondents themselves decide whether to be included Definitions

  9. Loaded Questions Misleading Graphs Abuses of Statistics • Bad Samples • Small Samples

  10. Figure 1-1 Salaries of People with Bachelor’s Degrees and with High School Diplomas $40,500 $40,500 $40,000 $40,000 30,000 35,000 $24,400 30,000 20,000 $24,400 25,000 10,000 20,000 0 Bachelor High School Degree Diploma Bachelor High School Degree Diploma (a) (b)

  11. We should analyze the numericalinformation given in the graph instead of being mislead by its general shape.

  12. Pictographs Abuses of Statistics • Bad Samples • Small Samples • Loaded Questions • Misleading Graphs

  13. Double the length, width, and height of a cube, and the volume increases by a factor of eight Figure 1-2

  14. Abuses of Statistics • Precise Numbers • Distorted Percentages • Partial Pictures • Bad Samples • Small Samples • Loaded Questions • Misleading Graphs • Pictographs

  15. “Ninety percent of all our cars sold in this country in the last 10 years are still on the road.”

  16. Deliberate Distortions Abuses of Statistics • Bad Samples • Small Samples • Loaded Questions • Misleading Graphs • Pictographs • Precise Numbers • Distorted Percentages • Partial Pictures

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