1 / 37

Critical Thinking 101 Statistics and Deception

References:. Asking the Right Questions

sandra_john
Télécharger la présentation

Critical Thinking 101 Statistics and Deception

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Critical Thinking 101 Statistics and Deception Gail P. Taylor, Ph.D. MBRS-RISE Program, UTSA

    2. References: Asking the Right Questions A guide to critical thinking. N. Neil Browne and Stuart Keeley. Prentice Hall, 2000.

    3. What is Critical Thinking? An awareness of interrelated critical questions that you employ at appropriate times Results in systemic, active evaluation of what you read and hear Influences how you react to information Accept? Reject? Withhold judgment Must also critically evaluate your OWN conclusions

    4. The Way of the World World- There will always be topics that are up for debate, with reasonable experts on both sides Laboratory- There will often be more than one interpretation for experimental results observed Some Facts are solid (measurements) Some more open to interpretation Social/Psych science is particular vulnerable

    5. Approach to Information Sponge Absorb everythingbut no value judgment Panning for Gold Ask about speaker motives Actively identify possible problems with what is being said? Evaluate identified problems? Form your own conclusions

    6. Beware Emotional Involvement with Opinions Everyone has pre-existing opinions The older the opinion, the more likely you didnt examine it May have great emotional attachment to un-examined opinions Do not fall in love with your ideas or opinions, so that they blind you to the truth

    7. In Science, Critical Thinking is used in your own Research The Scientific Method itself involves critical thinking Observe problem/phenomenon/conceive ideas Make Predictions/Develop a hypothesis Devise a test/Formulate experiment Carry out experiments Draw conclusions from results Reject or support hypothesis Revamp experiment and continue onward VITAL for a scientist. Impressive for a science student Need to take time to read and think

    8. And When You look at Others Research Results Are the ideas supported by the literature? Are the techniques correct? Was data analyzed correctly? Are their conclusions supported by the data?

    9. The Right Questions What is the issue/problem? What are the conclusions? What is the supporting evidence or reasons? Are any significant words or phrases ambiguous? How good is the evidence? Are the statistics deceptive? Are there hidden assumptions? Are there any fallacies in the reasoning? What significant information is omitted? Are there rival causes/theories? Are the conclusions reasonable?

    10. How to Find Issues

    11. What is the Issue? Given: They are trying to influence your beliefs What question (or controversy) are they trying to influence your beliefs ABOUT? In the World often about personal agendas In Science, can be to persuade you to the validity of their results and viewpoint/theory about a field.

    12. Where and How to Find the Issue: Often very obvious Generally found at beginning Sometimes only implied Its the question being addressed Inferred through conclusion Inferred through examination of authors associations They are trying to influence my view ofWhat??

    13. Explicit Issue: The question Im raising is: Why must we have speed limits on our highways?

    14. Implied Issue By now, more than two years after voters overwhelmingly approved the lottery, it has been proven that the game is not a success; in fact, it can be considered a failure What is the author reacting to? Issue: What is the impact of the Lottery?

    15. Two Types of Issues Sometimes difficult to discern Descriptive (how the world IS): Usually see in science What is the molecular basis for hibernation? Who decides to reduce the drinking age? Do families with pets argue less frequently? Prescriptive (How the world should BE) Ethical/Moral Should we reduce the drinking age? What ought to be done about welfare?

    16. Conclusions Given: They are trying to influence your beliefs What are they trying to get me to conclude?

    17. Finding Conclusions Often at the end (but not always) Often accompanied by specific phrases

    18. Finding a Conclusion We conclude that Results indicate Consequently Hence Therefore Thus In short It follows that Shows that Indicates that Suggests that It should be clear that We may deduce that Points to The point Im trying to make is The most obvious explanation It is highly probably that Proves that The truth of the matter is

    19. By now, more than two years after voters overwhelmingly approved the lottery, it has been proven that the game is not a success; in fact, it can be considered a failure Conclusion? Conclusion: The lottery is not a success and is in fact a failure

    20. Example Divorce is on the increase, and were worried. Finally, Psychologists have identified a key cause of divorce. Noticing that certain families have multiple divorces, they found that inherited genes play a major role in causing divorces. Although overall divorce rate is 20 percent, psychologists have discovered that a twin has a 45 percent rate of divorce if the identical twin has already experienced a divorce. Additional confirming evidence for genes as a primary cause stems from looking a the divorce rate of twins parents. If their parents have divorced, each twin has a 10 percent higher risk of divorce Issue: What is the cause of Divorce? Conclusion: Inherited genes are a major cause

    21. Quick Talk about Stats! Statistics 101 Statistics- Evidence expressed as numbers Can and often DO lieesp. in popular press Can also seem counter-intuitive to people

    22. Humans, Risk and Stats Statistics may seem counter-intuitive Automobile Deaths: 1.7 deaths per 100 million veh. miles Population risk per year: 1 in 6,300 Air Carrier Deaths: 0.7 deaths per 100 million aircraft miles 0.19 deaths per million aircraft departures Population risk per year: 1 in 1,568,000

    23. General Strategies to Detect Statistical Deception How were the statistics obtained? What are the Motivations of quoter? What does average mean? Are the conclusions supported by the stats? Is all the information needed for evaluation there?

    24. How Obtained Unknowable Statistics There are obstacles to getting accurate statistics on some topics Physical barriers to obtaining information Failure to report events Improper sampling Deception Educated Guesses Have to analyze what the person stating the stats has to gain.

    25. Is there a truly a perfect way to find out the following? Number of Aids cases? Number of Abortions? How many people shoplift? Have affairs? Have a mental disorder? Use cocaine? Commit white-collar crimes? Are homeless? Beat their wives?

    26. Biased Statistics Bad Initial Sampling We randomly polled 500 people from California, Florida, and Maine and have concluded that 34% of Americans prefer to live near the beach We went to a fundamentalist Mosque to find out what Muslims think

    27. Averages: Americans are better off than ever; the average salary of an American worker is now $28,400. The average pollution of air by factories is now well below the dangerous level.

    28. Beware of Average Mean: Add all values and divide by n Median: List all values, low to high, then take center (half above, half below) Mode: Value that appears most frequently

    29. Average salary? Mean- very high salaries of few skew the average, badly. Use if you want to inflate average salary Median & Mode not effected

    30. Average Pollution What happens if only a few factories are very very horrible polluters, at above an extremely harmful level? Median & Mode No danger Mean? - Very bad, on average. Chrome Plating shops

    31. With Averages also Need Range and Distribution Range gap between smallest and largest Distribution How frequently each value occurs. Ex: Average mercury content in fish is very low What happens if 10 percent have dangerous levels? On average, only 0.2 percent of landmines in the 25 fields were still active

    32. Averages, Range and Distribution. America is not overcrowded. Nationally, we have fewer than 60 people per square mile, a population density lower than that of most other countries Some areas really ARE crowded. Some are mostly unpopulated

    33. When an average is presented. Check which type of Average youre seeing See if the range and distribution might be important

    34. Prove One Thing, Conclude Another. A car dealer considered a particular car a big success because only 5 out of 100 buyers who bought the car had complained to the dealership about its performance. When 95 percent of buyers are pleased, the salesman says, then thats a darn good car Assumptions?

    35. How would you get this conclusion? Conclusion: Car was a high quality success Was this supported? Blind yourself to communicators statistics How would you actually test this? Random sample of many of this cars buyers and ask them how pleased there are with the car.

    36. Second Strategy, What Do Stats Say? Look at Stats alone Only 5 out of 100 buyers who bought the car had complained to the dealership about its performance. What can you conclude from this?

    37. Example Almost one-fourth of children are arsonists. Children all over the country were surveyed. Of the 90 who replied to the survey, 24 percent said that they knew of instances in which children set fires. Problem??

    38. Example II Women are better drivers than men, as proven by the fact that of men involved in accidents, 23 percent had been drinking-compared to 9.6% of women Problem?

    39. Deception by Omission Ask yourself, What further information do you need before you can judge the impact of the statistics?

    40. Evaluate: Fizz aspirin works 50 percent faster Than what???? Funding for AIDs research is more than adequate. Last year the government spent over 1.2 billion on AIDS research. How does this compare Over time? Other diseases? Total budget? College degrees pay off. A recent survey found that workers with a bachelors degree were earning an average of $35,000 per year in the spring of 2000. Where is the comparison of equally intelligent non-college students? What type of average?

    41. Evaluate: A crime wave has hit our city. Homicides have increased by 67 percent in the last year Problem- What are the absolute numbers? 3 to 5, versus 300 to 500

    42. Conclusions Ask How does the author or speaker know? What are their motivations? How did they choose their sample? Be curious about types of averages Blind yourself to the stats and see what stats you would want to support conclusions. Do they match? Look only at Stats and form your own conclusion. Does it match? What information is missing? Take care with misleading numbers and percentages and for missing comparisons.

More Related