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Research Methods in Science

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  1. Research Methods in Science UC LEADSSummer 2003Lecture 1

  2. Research Methods in Science: Outline of talk • Overview of general principles of the scientific method • Philosophy of science • examine objections • Bayesian and frequentist approach • Humanistic side of science • Ethics in science (case studies) • Scientific writing

  3. What do you think the scientific method is?

  4. Elementary Scientific Method • Hypothesis formation • Hypothesis testing • Deductive and inductive logic • Controlled experiments, replication, and repeatability • Interaction between data and theory • Limits to science’s domain

  5. The Scientific Method (“mission statement”) • The scientific method is the process by which scientists, collectively and over time, endeavor to construct an accurate (that is, reliable, consistent and non-arbitrary) representation of the world

  6. General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony • Science’s presuppositions, domains, and limits

  7. Hypothesis generation and testing • Formulation of a hypothesis to explain a phenomena • “Educated guess” • A hypothesis must be falsifiable

  8. A hypothesis must be falsifiable • The Loch Ness Monster is alive and well • The Loch Ness Monster does not exist • There is life on Mars • There is no life on Mars • DNA is the genetic material of all life • DNA is not the genetic material

  9. } Treatments, controls,independent & dependent variables,etc. Hypothesis Generation and Testing Based on my (or someone else’s) observations, I predict that: • H0: no differences • HA: significant difference

  10. } Treatments, controls,independent & dependent variables,etc. Let’s do an Experimental Test!!

  11. Experimental Tests: What are the main features? • Clear hypothesis • Identify independent and dependent variables • Assign controls • Repeatable, hence verifiable results • Used to support or refute claims

  12. General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic

  13. Deductive and Inductive Logic (distinction #1) • The conclusion of a deductive argument is already contained implicitly in its premises • The conclusion of an inductive argument goes beyond the information in its premises

  14. Deductive and Inductive Logic (distinction #2) • Given the truth of all of its premises, the truth of an inductive argument’s conclusion follows with at most high probability • Deduction argues from a given model’s general principles to specific cases of expected data

  15. Deductive and Inductive Logic (distinction #3) • Deduction argues from a given model’s general principles to specific cases of expected data • Induction argues in the opposite direction, from actual data to an inferred model

  16. Deductive and Inductive Logic • One is based on statistics (inductive) • The other is based on probability

  17. Deductive and Inductive Logic(telling the difference) Given: A “fair coin” is one that gives tails with probability 0.5 and head 0.5 . • Problem 1: Given that a coin is a fair coin. What is the probability that the coin will produce 45 heads and 55 tails? • Problem 2: Given that 100 tosses of a coin produce 45 heads and 55 tails. What is the probability that the coin is a fair coin?

  18. Why is induction so pervasive and critical in science? Science is almost entirely about unobservables -- about things and times outside the database of actual observations. Iron melts at 1,535°C (but everywhere?) Water boils at 100°C (but everywhere?)

  19. The basis of induction: Aristotle • Aristotle (384-322 BC) offered 3 methods of induction • Unifying concept: in deductive arguments, which are composed of premises, inductive arguments are the scaffolds that raise the status of the deductive argument to a law-like status

  20. The basis of induction: Aristotle • Dialectical induction (Topics). Not entirely relevant to scientific research, but useful: • mentor to pupil discourse • “If a skilled pilot is the best pilot and the skilled charioteer is the best charioteer, then, in general, the skilled [person] is the best [person] in any particular sphere” (Perez-Ramos 1988)

  21. The basis of induction: Aristotle • Enumerative induction (Prior Analytics). Statements about individual objects provide the basis or premises for a general conclusion: • from observing numerous adult humans, an inductive argument could conclude that all humans have 32 teeth

  22. The basis of induction: Aristotle • Intuitive induction (Posterior Analytics). Direct intuition of the general principles exemplified in the data: • bright side of the mood always faces the sun, so the moon shines because of reflected sunlight

  23. General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony

  24. Parsimony • Shortest path or the less complex “explanation” to the “true state of nature” A B

  25. Parsimony • Keynes (1962) expressed parsimony as the law of the limited variety in nature • Iron melts at 1,535°C • unlimited nature…unique atoms…unique properties…no iron, oxygen, no humans (sum of the parts) • 100 chemical elements • related presuppositions of induction

  26. Parsimony • The principle of parsimony recommends that from among theories fitting the data equally well, scientists choose the simplest theory. • Thus, the fit of the data is not the only criterion bearing on the theory choice

  27. Parsimony • Additional criteria includes: • predictive accuracy • explanatory power • testability • fruitfulness in generating new insights and knowledge coherent with other scientific and philosophical beliefs • repeatability of results

  28. Parsimony • Q: Why is parsimony an important principle in science? . • A1: The entire scientific enterprise has never produced, and never will produce, a single conclusion without invoking parsimony • A2: Economy…facilitate insight, improve accuracy, and increase efficiency

  29. General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony • Science’s presuppositions, domains, and limits

  30. Science’s presuppositions, domains, and limits • Set of beliefs that allow a person to validate her observations, results, conclusions (objectivity of science) • constancy of the universe • parsimony • Acceptance and acknowledgement of the knowable and the unknowable

  31. General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony • Science’s presuppositions, domains, and limits

  32. How do we represent this set of principles that found in all of the sciences? General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony • Science’s presuppositions, domains, and limits…

  33. } SCIENTIFICMETHOD General principles that pervade all of the sciences • Hypothesis generation and testing • Deductive and inductive logic • Parsimony • Science’s presuppositions, domains, and limits

  34. } SCIENTIFICMETHOD General principles that pervade all of the sciences There are detractors of the idea that a scientific method, upon which we are able to make claims about the true state of nature, does not exist

  35. General principles that pervade all of the sciences } There are detractors of the idea that a scientific method, upon which we are able to make claims about the true state of nature, does not exist Philosophical&Scientific

  36. cannot General principles that pervade all of the sciences } Paul Feyerabend insisted that there are no objective standards of rationality, so naturally there is no logic or method to science…“anything goes” in science…it is no more productive of truth than “ancient myth-tellers, troubadours and court jesters” Philosophical

  37. cannot General principles that pervade all of the sciences } Thomas Kuhn is critical of what he sees as modernist misrepresentation of the nature of science: Modernist definitions of science claim that science is objective because it is empirical (based only on the data of our senses), rational (reasonable, or logically defensible) and that its presuppositions are obviously true... Scientific

  38. cannot General principles that pervade all of the sciences } Kuhn claims science is a social enterprise and as such is also quite subjective. He argues that, "every individual choice between competing theories depends on a mixture of objective and subjective factors." Scientific

  39. cannot General principles that pervade all of the sciences } Instead, science occurs in revolutions where old ideas are thrown out and new ones accepted. Science is therefore capricious, and each discipline of science cannot share a set of pervading principles Scientific

  40. cannot General principles that pervade all of the sciences } These revolutions are called PARADIGM SHIFTS Scientific

  41. astronomy chemistry geology physics biology

  42. astronomy chemistry geology physics biology General principles and technologies are distinct to each scientific discipline

  43. Thought experiment • You have been awarded a $500,000 grant and can spend it on any type of equipment that is relevant to your research. • Make a list of what you will buy and justify it (don’t worry about EXACT price values as you essentially can afford almost anything!) • (don’t forget about Gregorio’s research!)

  44. Thought experiment • Can you safely say that you will not rely on or utilize any of the following principles by using your new equipment?: hypothesis generation and testing Deductive and inductive logic Parsimony Science’s presuppositions, domains, and limits

  45. “you” “them”