Can Science Cure the Common Cold? Introduction to the Scientific Method

1. Chapter 1 Can Science Cure the Common Cold? Introduction to the Scientific Method 0

2. 1 The Process of Science Science refers to a body of knowledge Science is not a giant collection of facts to be memorized. It important to learn about the process of science called the scientific method. The scientific method allows the solving of problems and answer questions. Observations Proposing ideas Testing the ideas Discarding or modifying ideas based on results

3. 1 The Process of Science The Nature of Hypotheses Hypothesis: proposed explanation for a set of observations Hypotheses needs to be: Testable – it must be possible to examine the hypothesis through observations Falsifiable –it must be able to potentially be proven false

4. 1 The Process of Science Where do hypotheses come from? Both logical and creative influences are used to develop a hypothesis

5. 1 The Process of Science Scientific Theory Powerful, broad explanation of a large set of observations Based on well supported hypotheses Supported by research from several different independent sources

6. 1 The Process of Science The Logic of Hypothesis Tests Inductive reasoning: combining a series of specific observations into a generalization to create a hypothesis

7. 1 The Process of Science The Logic of Hypothesis Tests To test the hypothesis use deductive reasoning: This involves using a general principle to predict an expected observation using if/then statements For example, If vitamin C decreases the risk of catching a cold, then people who take in additional Vitamin C will get less colds.

8. 1 The Process of Science The Logic of Hypothesis Tests The process looks something like this:

9. 1 The Process of Science

10. 1 The Process of Science The Logic of Hypothesis Tests A hypothesis that fails our test is rejected and considered disproven. A hypothesis that passes is supported, but not proven. Why not? An alternative hypothesis might be the real explanation.

11. 2 Hypothesis Testing The most powerful way to test hypotheses: do experiments Experiments support the hypothesis that the common cold is caused by a virus.

12. 2 Hypothesis Testing The Experimental Method Experiments are designed to collect data or information to test specific hypotheses. Variables: factors that can change in value under different conditions Independent variables can be manipulated by the scientist Dependent variables cannot be changed by the researcher

13. 2 Hypothesis Testing Controlled Experiments Controlled experiment: tests the effect of a single variable Control: a subject who is not exposed to the experimental treatment but has all other variables the same

14. 2 Hypothesis Testing Controlled Experiments Differences seen between the experimental group and control group can be attributed to the experimental treatment. Random Assignment An effective way of assigning individuals to groups for testing

15. Animation: Science as a Process: Arriving at Scientific Insights Click “Go to Animation” / Click “Play”

16. 2 Hypothesis Testing Controlled Experiments Example: Echinacea tea experiment: Hypothesis: drinking Echinacea tea relieves cold symptoms Experimental group drinks Echinacea tea 5-6 times daily. Control group drinks “sham” Echinacea tea 5-6 times daily (placebo). Both groups rated the effectiveness of their treatment on relieving cold symptoms.

17. 2 Hypothesis Testing Controlled Experiments People who received echinacea tea felt that it was 33% more effectiveat reducing symptoms.

18. 2 Hypothesis Testing Minimizing Bias in Experimental Design If human subjects know whether they have received the real treatment or a placebo, they may be biased. Blind experiment: subjects don’t know what kind of treatment they have received Double blind experiment: the person administering the treatments and the subjects do not know who is in each gropu until after the experiment is over

19. 2 Hypothesis Testing Minimizing Bias in Experimental Design

20. 2 Hypothesis Testing Using Correlation to Test Hypotheses The “gold standard” for experimentation Double-blind, placebo controlled and randomized experiments Model systems can be used in experiments when it appears to dangerous or unethical to test on humans examples: mice, rats, dogs and pigs A correlation can be used to test hypotheses when controlled experiments on humans is impossible to perform

21. 2 Hypothesis Testing Using Correlation to Test Hypotheses Using existing data, is there a correlationbetween variables? Hypothesis: stress makes people more susceptible to catching a cold Is there a correlation between stress and the number of colds people have caught?

22. 2 Hypothesis Testing Using Correlation to Test Hypotheses Results of such a study: the number of colds increases as stress levels increase. Caution! Correlation does not imply causation.

23. 2 Hypothesis Testing Using Correlation to Test Hypotheses The correlation might be due to other reasons.

24. 2 Hypothesis Testing

25. 3 Understanding Statistics Overview: What Statistical Tests Can Tell Us Statistics in science is used to evaluate and compare data. We can extend the results from small samples to an entire population using statistical tests. Statistically significant: results of difference between groups is due to random chance and not an error in experimenting

26. 3 Understanding Statistics The Problem of Sampling Error Sampling error: the effect of chance on experimental data We can calculate the probability that a result is simply due to sampling error. Confidence interval: the range of values from a sample that has a 95% probability of containing the true population mean (average)

27. 3 Understanding Statistics The Problem of Sampling Error

28. 3 Understanding Statistics Factors that Influence Statistical Significance Sample size The true difference between populations Bigger is better: more likely to detect differences

29. 3 Understanding Statistics Factors that Influence Statistical Significance

30. 3 Understanding Statistics What Statistical Tests Cannot Tell Us If an experiment was designed and carried out properly If observer error occurred, only can evaluate the probability of sampling error May not be of any biological significance

31. 4 Evaluating Scientific Information Primary Sources Researchers can submit a paper about their results to a professional journal (primary source). Primary Sources undergo peer review: evaluation of submitted papers by other experts Secondary sources: books, news reports, the internet, and advertisements

32. 4 Evaluating Scientific Information Information from Anecdotes Anecdotal evidence is based on one person’s experience, not on experimental data. Example: a testimonial from a celebrity

33. 4 Evaluating Scientific Information Science in the News

34. 4 Evaluating Scientific Information Science in the News Secondary sources may be missing critical information or report the information incorrectly. Consider the source of media reports. Be careful with the internet since anyone can post information. Be very cautious about claims made in paid advertisements.

35. 4 Evaluating Scientific Information Understanding Science from Secondary Sources Use your understanding of the process of science to evaluate science stories. News media generally highlight only those science stories that seem newsworthy. They are more likely to report a positive result than a negative one.

36. 5 Is There a Cure for the Common Cold? No, but prevention methods are known. Wash your hands! No effect on cold susceptibility: Vitamin C Exposure to cold temperatures Exercise No vaccine for the common cold

37. A(n) ________ is a proposed explanation for a single observation. scientific method hypothesis scientific theory experiment

38. A(n) ________ is a proposed explanation for a single observation. scientific method hypothesis scientific theory experiment

39. Which of the following is a scientific hypothesis? Jazz is better music than rap. Garden fairies make tomatoes grow better. Hunting species to extinction is wrong. Increasing the amount of protein in a cow’s diet increases her milk yield.

40. Which of the following is a scientific hypothesis? Jazz is better music than rap. Garden fairies make tomatoes grow better. Hunting species to extinction is wrong. Increasing the amount of protein in a cow’s diet increases her milk yield.

41. Which of the following is correct? A hypothesis can be wrong. A hypothesis is not always testable. A hypothesis can prove a person’s values. A hypothesis should be formed before making any observations.

42. Which of the following is correct? A hypothesis can be wrong. A hypothesis is not always testable. A hypothesis can prove a person’s values. A hypothesis should be formed before making any observations.

43. Which of the following statements was developed using deductive reasoning? People who take in large amounts of caffeine are irritable. If subjects take in large amounts of caffeine, then it will increase irritability. Large amounts of caffeine has shown to increase irritability. Irritability has been shown to increase with a decrease in caffeine consumption.

44. Which of the following statements was developed using deductive reasoning? People who take in large amounts of caffeine are irritable. If subjects take in large amounts of caffeine, then it will increase irritability. Large amounts of caffeine has shown to increase irritability. Irritability has been shown to increase with a decrease in caffeine consumption.

45. In an experiment, Dr. Smith feeds different amounts of protein to dairy cows and measures the differences in their milk yields. What is the independent variable in Dr. Smith’s experiment? time milk yield amount of protein placebo

46. In an experiment, Dr. Smith feeds different amounts of protein to dairy cows and measures the differences in their milk yields. What is the independent variable in Dr. Smith’s experiment? time milk yield amount of protein placebo

47. What is happening in step #2 in the diagram? The virus is introducing its genetic material into the cell. The host cell is killed. Copies of the virus are being made by the host cell. The virus is being destroyed by the host cell.

48. What is happening in step #2 in the diagram? The virus is introducing its genetic material into the cell. The host cell is killed. Copies of the virus are being made by the host cell. The virus is being destroyed by the host cell.

49. What does this graph show? There is no difference between placebo and zinc lozenges. Taking placebo lozenges causes people to have more types of cold symptoms. Zinc lozenges lead to people catching fewer colds. People taking zinc lozenges show cold symptoms for a shorter period of time.

50. What does this graph show? There is no difference between placebo and zinc lozenges. Taking placebo lozenges causes people to have more types of cold symptoms. Zinc lozenges lead to people catching fewer colds. People taking zinc lozenges show cold symptoms for a shorter period of time.