Research Methods

Research Methods Unit 2 (Chapter 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

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.

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.

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.

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.

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.

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

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

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

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

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

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

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

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

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

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

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?

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

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

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

Figure 2.13 Positive and negative correlation

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

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

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

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….

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.

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

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

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

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

Research Methods