The Scientific Method

Transcription

1 The Scientific Method August 28, 2014 in class surveys o will ask questions about the survey from the first day of class o What is the pattern? o preventable medical error: on the consensus of uncertainty o is astrology testable o 16. seasons due to elliptical orbit: not true because it also has to do with the tilt of the axis o 14. aliens landed here: conjunction fallacy, if you want more people to believe something, then wrap it in a conspiracy theory o optical illusions and consideration of some responses from last time! our brains are not inherently rational! we need a formal method for decision making why we believe certain things o experience o education o cultured background o evidence o media exposure why the different responses within the questions (focus of the class) o a. using different rules or criteria o b. basing our responses on different evidence o c. inherent uncertainty in some of the statements (not all statements were equally prone to falsification) miscellaneous reasons o thinking fast and slow: when you have to focus more on reading it and more material you get more wrong because your brain slows down o a. did not think it through o b. alternative interpretations of the question The Scientific Method September 3, 2014 quiz due Friday sayings o time flies like an arrow but fruit flies like a banana o there once was a man from Nantucket how is the lamp activated o heat, warmth of my hand (lighter doesn't activate it) o pressure/vibration from hand (hitting it with a notebook and smashing it doesn't work) o motion to turn on switch (doesn't activate it) o grounding it when I touch the metal (light does activate when the insulated cord is touched so it's not grounding) o when a warm body, full of salt water, comes near it, it is activated both demos illustrate a crude form of scientific method it's basically trial and error (Really all the SM is)

2 Try something, see if it works. If not, try something else. scientific method o 1. goal: figure out a phrase, understand how the lamp works o 2. model: guesses as to the words in the phrase, guesses about the lamp mechanism o 3. Data: observations made to test the model, where the letters went in words, what the lamp did when bumped, burned, ect.) o 4. evaluation/conclusion: deciding if the model agrees with the data o 5. revision: replacing old models with new ones, only if the old model is rejected or if the data fit new model better we spend the most time on models, data, and conclusion first exam: model and data how pieces fit together Goal > model > evaluation < data Revision (new model) get more data Reject model accept model properties and consequences of SM o 1. Evidence is the standard for judging a model. Science is not a poll, issues not decided by majority, politics, social merit o 2. science does not accept explanations or models that lack supporting evidence o 3. Cyclical: there are continual efforts to improve. There is often note an endpoint. (new data may always change your conclusions) hence no proving a model o 4. uncertainty is acceptable: most tests of a model will result in not being sure whether to reject or not o 5. Disagreement over a test is okay. As evidence pours in, consensus should emerge o 6. progress: we expect our models/understanding to improve over time (not guaranteed) progress over 100 years o old music player o old plane in early 1900's o science and technology are very closely related examples of progress o radiation and health! early 1900's! no biological concern! 1929 found that x-rays cause genetic damage, happened at UT, guy won a Nobel prize! why were we socially concerned about it? it fed into eugenics and created mutations affecting the future generation and their intelligence (gene pool)! radical change in our understanding from the 1950's on that radiation causes cancer, learned this from the data, dropped two atomic bombs on japan and we sent people over there and saw the cancer rates went up and their kids were fine o health effects of smoking! no concern originally, people were dying of infectious diseases before lung cancer! lung cancer 1940's on! now concerned with emphysema, heart disease! effects on the fetus! second hand smoking! led to a ban on smoking many standard uses of SM o current event about politics and the SM

3 The Scientific Method September 5, 2014 many non standard uses of SM o advertising: to figure out what people will buy o politics: sending different messages out in different areas, Democrats o wright brothers (in book): successful in first man powered airplane, trying things out shortcut to figuring it out if it's science, meets the criteria of good science o a. is the use of evidence paramount? o b. is there continual revision/turnover? -not work with simple example examples of when it's not quite science (institutions that fail on one or more elements) o 1. criminal trial! a. goal: determine and decide if someone should be held accountable! b. model: defendant committed crime or not! c. data: evidence in the trial! d. evaluation: jury's verdict! e. revision: reconsideration of original verdict o Charlie Chaplin was sued for paternity, blood evidence said he wasn't the father and the jury convicted him o 4 girls were murdered in a yogurt shop in Austin and the place was set on fire, put people on trial and some had been raped before they were murdered and the DNA didn't match the people convicted, they could not suppress the evidence weak points o c. critical evidence can be suppressed, jury can ignore evidence o e. revision difficult: you can't be retried for the same crime (double jeopardy), cannot go back and retry, difficult to get retry even with new evidence o 4 girls were murdered in a yogurt shop in Austin and the place was set on fire, put people on trial and some had been raped before they were murdered and the DNA didn't match the people convicted, they could not suppress the evidence o 2. astrology! goals: predict the future! model: rules based on "stars"! data, evaluation, revision: absent, just test which prediction work to get a set of rules o 3. religion! there is no pretense of using the scientific method, the bible and other religious writings would be continuously changing! no one is trying to prove it right or wrong where science belongs o decisions should be informed by the best evidence (SM) but not dictated by it o issue --> evidence/scientific conclusions and social/political/legal consequences of alternative policies -- > policy o we don't want a new science to dictate morals and ethics

4 Models September 5, 2014 what they are, why and how used, and limitations model o anything (idea, plant, object, organism) used to represent something else as a shortcut to achieve a goal examples o model organisms in biology: for genetics of humans Model organism phage Bacteria Yeast Flies Worms Fish Mice Finding DNA is genetic material, foundation of molecular genetics, they eat bacteria and create small circles, compact, fast, can go from 1-10 million, study mutations and how heritage works, really useful because of their speed relationship of genes to physiology, basic of many infectious diseases, grow a little more slowly than viruses, and have a physiology unlike viruses, time scale and compactness are convenient Control of all cell division, relationship of genes to proteins, useful for cancer x-rays cause genetic damage, done at UT program cell death, important in development Developmental genetics Mice the most important modern organism for humans sake, 99% of our genes that have a counterpart in mice genes scale models o solar system: the smallest sphere was correct, distance was on the far side of the stage o pictures: models of objects, ad for the back of the phone book: model family, found almost the same family on the back of a brochure o past: model of the future o participants in drug trial: model of customers with approval, the people who are going to take the drug when it's marketed o resume: model of a person, Remus Reid's resume sounds like a good citizen but he was really a criminal Models September 8, All models are false- every model has limitation for what it represents, no such things as a perfect model o We use the models when the limitations don t matter or we don t know better o We want to be aware of the limitations, however be they might matter 2. How serious the limitation are dependent on the goal o Think in this way: x is a model of y to achieve goal w o For example a mouse is a model of humans is good for many aspects of understanding human genetics o Mouse as a model for DWI improvement, it would be horrible to use human 3. A model can be useful in different ways

5 o o o a: accuracy (similarity to what the model represents) c: convenience (how easy is model to apply or use; cost, time, ethics) u: uniformity (how similar model is from one copy/use to the next) Table: Model of Humans for Genetics model Represents Accuracy convenience Humans Humans 1 5 Monkeys Humans 2 4 Mice Humans 3 3 Yeast Humans 4 2 Bacteria Humans 5 1 *used chimps for polio 4. Three types/classes of models o a. abstract (ideas, math, computer, numbers, graphs, plans, ect.) o b. physical (touchable, organisms, structures, demos, ect.) o c. sampling (the way subjects are chosen for a study, ex. random is an obvious sampling model) o map could be physical and abstract 2 lesson points 5. one-to-many, many-to-one o no such things as just one model of something, any one thing can be a model of many 6. pieces and parts as models o a model of something can be a small part of that something o 747 went down during the Olympics and everyone though terrorism, accuracy and convenience, a mode could be a part of the plane five matters to address with any model o 1. the goal o 2. what the model is o 3. its application- what the model represents o 4. how it may be useful for the goal o 5. what its limitations are for the goal link on we page o antihistamine works differently for people o limitations: that specific antihistamine may have different symptoms o Using generic lit. is a model is cheaper and has the same active ingredient, but the two may have different actions due to different things in the pill o the first boxes may be expired, any box is probably a really good model of any other box o went over posted page over relief a list of some prominent model failures in history o a lottery not quite random (1969 the draft lottery for Vietnam, most males couldn't go to college, assign birthdays of priority so everyone had an equal chance of going, put all he birthdays in an urn and drew out birthdays, but it really wasn't mixed up that well, set draft priorities and the mixing of capsules with birthdays was not adequate, folks with birthdays in December came out disproportionately low or drafter earlier o NASA 1990, Hubble telescope, had an mirror problem if they would've fixed it on earth, abstract model of assembly in air