Scientific Approach: Steps and Terminology

1. Research Methods Unit 2 (Chapter 2)

2. The Scientific Approach • Empiricism • Basic assumption: events are governed by some lawful order • Goals: • Measurement and description • Understanding and prediction • Application and control • Goal of theory testing in science: refutation not proving

3. Steps of the Scientific Method • 1. Developing a Hypothesis: -Hypothesis: A statement predicting the outcome of a scientific study or describing the relationship among variables in a study.

4. Steps of the Scientific Method • 2. Design test: A hypothesis must undergo rigorous tests before it will be accepted as a legitimate theory. • To make a test controlled, one must account for the independent variable. • Independent Variable: A stimulus condition that the experimenter changes independently of all other carefully controlled conditions in the experiment.

5. Steps of the Scientific Method • 3. Collect data: getting information by direct observation that relies only on the independent variable and not on the experimenter’s hopes. This data is called the dependent variable. • Dependent Variable: The measured outcome of a study, or the response of the subjects in the study.

6. Steps of the Scientific Method • 4. Analyzing the results: This step consists of looking at the data collected and seeing if it supports or disproves the hypothesis.

7. Steps of the Scientific Method • 5. Publishing, criticizing and replicating the results: The last step of the scientific method is to have the results withstand the criticism and scrutiny of the science community. • Replicate: To do a study over to see if the same results are obtained. To control for bias, the replication is most often done by someone other than the original researcher.

8. The Scientific Method: Terminology • Operational definitions are used to clarify precisely what is meant by each variable • Participants or subjects are the organisms whose behavior is systematically observed in a study • Data collection techniques allow for empirical observation and measurement

9. The Scientific Method: Terminology • Statistics are used to analyze data and decide whether hypotheses were supported • Findings are shared through reports at scientific meetings and in scientific journals – periodicals that publish technical and scholarly material • Advantages of the scientific method: clarity of communication and relative intolerance of error • Research methods: general strategies for conducting scientific studies

10. Experimental Research: Looking for Causes • Experiment = manipulation of one variable under controlled conditions so that resulting changes in another variable can be observed • Detection of cause-and-effect relationships • Independent variable (IV) = variable manipulated • Dependent variable (DV) = variable affected by manipulation • How does X affect Y? • X= Independent Variable, and Y= Dependent Variable

11. Experimental and Control Groups • Experimental group – subjects who receive some special treatment in regard to the independent variable • Control group – similar subjects who do not receive the special treatment • Logic: • Two groups alike in all respects (random assignment) • Manipulate independent variable for one group only • Resulting differences in the two groups must be due to the independent variable • Extraneous and confounding variables

12. Experimental Designs: Variations • Expose a single group to two different conditions • Reduces extraneous variables • Manipulate more than one independent variable • Allows for study of interactions between variables • Use more than one dependent variable • Obtains a more complete picture of effect of the independent variable

13. Descriptive Research Methods • Strategies for observing and describing behavior • Typically words instead of numbers (qualitative) • Do not manipulate anything in the research

14. Observations • Observe behavior by watching and recording information • Naturalistic – in the natural setting, creates a purer result • Lab – more controlled, but less natural

15. Case Studies • One individual studied in great detail • Typically rare cases • You collect information in several ways

16. Surveys • Asking questions about a specific topic • Very direct • Use interviews, questionnaires, surveys

17. Statistics and Research • Statistics – using mathematics to organize, summarize, and interpret numerical data • Descriptive statistics: organizing and summarizing data • Inferential statistics: interpreting data and drawing conclusions – use of probability

18. Descriptive Statistics: Measures of Central Tendency • Measures of central tendency = typical or average score in a distribution • Mean: arithmetic average of scores • Median: score falling in the exact center • Mode: most frequently occurring score • Which most accurately depicts the typical?

19. Descriptive Statistics: Variability • Variability = how much scores vary from each other and from the mean • Standard deviation = numerical depiction of variability • High variability in data set = high standard deviation • Low variability in data set = low standard deviation

20. Normal Distribution A normal distribution is a bell shaped curve. A standard deviation of 1 accounts for about 68% of responses.

21. Descriptive Statistics: Correlation • When two variables are related to each other, they are correlated. • Correlation = numerical index of degree of relationship • Correlation expressed as a number between 0 and 1 • Can be positive or negative • Numbers closer to 1 (+ or -) indicate stronger relationship

22. Figure 2.13 Positive and negative correlation

24. Which of the following correlation coefficients presents the strongest relationship between the variables? a. .02 b. -.67 c. .55 d. -.14

25. Correlation: Prediction, Not Causation • Higher correlation coefficients = increased ability to predict one variable based on the other • SAT/ACT scores moderately correlated with first year college GPA • 2 variables may be highly correlated, but not causally related • Foot size and vocabulary positively correlated • Do larger feet cause larger vocabularies? • The third variable problem

26. Inferential Statistics: Interpreting Data and Drawing Conclusions • Hypothesis testing: do observed findings support the hypotheses? • Are findings real or due to chance? • Statistical significance = when the probability that the observed findings are due to chance is very low • Very low = less than 5 chances in 100/ .05 level • Other factors might account for the results

27. Sampling • Representative Sample: A sample obtained in such a way that it reflects the distribution of important variables in the larger population in which the researcher are interested-variables such as age, SES, ethnicity, education….

28. Evaluating Research: Methodological Pitfalls • Sampling bias • Placebo effects – is not always uniform – cost factors and perceived pain • Distortions in self-report data: • Social desirability bias • Response set • Experimenter bias • the double-blind solution • Research protocol of clinical trial for drugs – FDA in U.S.

29. Internet Psychological Research • Internet-mediated research refers to studies in which data collection occurs over the web. • Possible Advantages • Samples that are much larger and much more diverse than the samples used in lab research • Have the potential to yield more diverse and representative samples

30. Internet Psychological Research • Potential Disadvantages • Sampling bias resulting from self-selection may be a more troublesome issue in Internet-mediated research • Web users tend to be younger, brighter, and more affluent than nonusers • Data are collected under far less controlled conditions than in traditional studies

31. Ethics in Psychological Research: Do the Ends Justify the Means? • The question of deception • The question of animal research • Controversy among psychologists and the public • Ethical standards for research: the American Psychological Association • Ensures both human and animal subjects are treated with dignity

32. Ethics in Psychological Research: Do the Ends Justify the Means? • Tuskegee Syphilis Study: • http://www.cdc.gov/tuskegee/timeline.htm