Unit 2: Research Methods

Section 1: The Scientific Approach

Section 2: Experimental Research

Section 3: Descriptive & Correlational Research

Section 4: Statistics

Section 5: Evaluating Research

Section 6: Ethics

Basic Concepts

· A theory is a system of ideas used to explain a set of observation.

· A hypothesis is a testable prediction derived from a theory. It is a testable statement about the relationship between two or more variables.

· A variable is any measurable condition, event, characteristic, or behavior that can be observed or controlled in a study.

Statistics is the use of math to organize, summarize, and interpret data.

Section 1: The Scientific Approach
Ref: pp.38-42

Goals of Science

1. Measurement and Description

2. Understanding and Prediction

3. Application and Control
Ref: Fig. 2.1, p. 39

The Scientific Method

1. Formulate a Testable Hypothesis.

2. Select the Research Method and Design the Study

3. Collect the Data

4. Analyze the Data and Draw Conclusions

5. Report the Findings
Ref: Fig. 2.2, p. 40, and Tab. 2.1, p. 41

Advantages of the Scientific Method

1. Clarity and Precision--avoids logic, casual observation, and common sense.

2. Intolerance of Error--scientists are trained to be critical thinkers.

Section 2: Experimental Research
Ref: pp.42-48

Experimental Research

· An experiment is a research method in which the researcher manipulates an independent variable to observe resulting changes in a dependent variable.

· For example, a researcher wants to examine the effects of stress on performance. The researcher can design an experiment which controls the level of stress the participants experience while performing a task. In this example, the level of stress is the independent variable and the quality of performance is the dependent variable.

· In running an experiment, the researcher will give the experimental group of participants special treatment with the independent variable. The control group of participants do not receive this treatment. This way the two groups are alike in all ways except with regard to the independent variable, thus allowing the researcher to measure the impact of the independent variable on the dependent variable.

· For example, a researcher believes a new drug may be useful for treating depression. Participants diagnosed with depression are then randomly assigned to either the experimental group or the control group. The experimental group receives the drug treatment, while the control group receives a placebo (a "drug" with no active ingredient). The two groups are then the same except for the use of the active drug, thus the researcher can isolate the effect of the drug (independent variable) on the depression (dependent variable).

· Extraneous variables are those variables other than the independent variable which can affect the dependent variable. An extraneous variable can confound a study. To control for this, researchers randomly select subjects into the control and experiment groups.

· For example, to ensure gender wasn't a confounding variable in a study, a researcher would randomly assign men and women to the experiment and control groups.

Variations in Experimental Design

1. Subjects can sometimes serve as their own control group. For example, to study the effect of noise on concentration, a researcher may give a group of participants a set of math problems to solve. Then the same people may be given another set of problems to solve while listening to loud noise. In this example, the subjects first are the control group (no special treatment) and then become the experiment group (receiving the special treatment).

2. More than one independent variable may be manipulated during an experiment. For example, besides studying the effect of noise on concentration, the researchers could also study the effects of different types of music or of lighting or room temperature on concentration.

3. More than one dependent variable may be studied during an experiment. For examle, the speed and accuracy of the problem solving could be observed.
Ref: Fig. 2.5 & 2.6, p.45

Advantages and Disadvantages of Experimental Research

· This is the only research method which allows researches to draw causal (cause and effect) conclusions about how one variable affects another.

· Experiments are often artificial. For example, a researcher who wants to examine decision making in juries could get twelve participants to make a decision on a case, but could never completely replicate a real jury preparing a real verdict for a real trial.

· Some things can't be studied through an experiment. For example, to demonstrate a causal relationship between smoking and cancer, a researcher would have to have a control group which didn't smoke and an experiment group that would smoke.

Section 3: Descriptive & Correlational Research
Ref: pp. 48-52

Descriptive & Correlational Approaches

· Naturalistic Observation allows a researcher to observe behavior in its natural setting. The researcher does not control or interfere with the subjects.

· Case Studies are in-depth investigations of individual subjects. This is useful for rare events or conditions.

· Surveys employ interview or questionnaires to gather information about specific aspects of subjects' behavior. This allows researchers to study large groups of people.

· All of these approaches allow researchers to study subjects outside of a laboratory setting. However, none of these approaches can conclusively demonstrate a causal relationship between variables.
Ref: Fig. 2.10, p.52

Section 4: Statistics
Ref: pp.53-57

Descriptive Statistics

· Descriptive statistics are used to summarize data.

· Descriptive statistics can measure central tendency.

· The median is the number which falls in the center of a set of data.

· The mean is the mathematical average of a set of data.

· The mode is the most frequent score in a set of data.

· Descriptive statistics can measure variability.

· Standard deviation is a measure of the amount of variability in a set of data.

· Descriptive statistics can measure correlation (the strength of the relationship between variables).

· The correlation coefficient is a measure of the degree of relationship between variables.

· The correlation coefficient is measured from -1.00 to +1.00. The close the coefficient to 0, the less a correlation exists. The closer a coefficient to -1.00 the stronger the negative correlation. The closer a coefficient to +1.00, the strong the positive correlation.

· For example, the relationship between gender and school marks would be low (close to 0), whereas the relationship between absences and school marks would be strong and negative (close to -1.00) and the relationship between hours of studying and school marks would be strong and positive (close to +1.00).

· Correlation is not causation Correlation does not show a causal relationship. For example, students who score high on the Grade 11 PE tend to do well in university. This is a strong, positive correlation. However, students do not do well in university because they did well on the PE. It is not a causal relationship.
Ref: Fig. 2.11, p.53, Fig. 2.12 & 2.13, p. 54, Fig. 2.14 & 2.15, p.55.

Inferential Statistics

· Inferential statistics are used to interpret data and draw conclusions.

· Inferential statistics are used to determine statistical significance, i.e., how probable it is that the observed findings are the result of chance.

Section 5: Evaluating Research
Ref: pp.57-61

Evaluating Research

· Replication is the repetition of a study to see whether the earlier results can be duplicated. Studies are replicated many times before the findings are generally accepted.

· A meta-analysis combines the statistical results of many studies into one set of data.

Flaws in Research

· Sampling bias occurs when a sample is not representative of the population from which it is drawn.

· The placebo effect occurs when participants' expectations lead them to experience change, even though there is no special treatment.

· Often people respond to research questions with the social desirability bias, in which they give answer which are socially desirable rather than accurate.

· Often people respond to questions without considering the content of the questions. This is called a response set.

· Experimenter bias occurs when a researcher's expectations about the outcome of an experiment affect it's outcome. This is controlled by the double-blind procedure, in which neither subjects or experimenters know which subjects are in the experiment group and which are in the control group.
Ref: Fig. 2.16, p.58

Section 6: Research Ethics
Ref: pp. 61-64

Deception

· Deception of participants has been common in psychological research since the 1960s.

· Some researchers oppose the use of deception because it involves lying to subjects, potentially undermining the subjects' trust in the experimenters, and may make the subjects feel bad when the deception is revealed.

· Most researchers support the use of deception because some issues cannot be studied without deception, there is no evidence that deception is inherently harmful to participants, and the benefits of deception outweigh the costs.

Animal Research

· Psychologists use animals for research because they want to learn about the animal behavior, or to compare the animal behavior to human behavior, or because certain treatments are unethical to be done on humans.

· Some researchers believe that it is wrong to subject animals to any harm for research purposes and that the results may not be applicable to humans.

· Most researchers support the use of animal research because of the advancement of science for treatment of human disorders.

APA Ethical Guidelines for Research

1. A subject's participation must be based on informed consent.

2. Participants should not be exposed to harmful or dangerous procedures.

3. If an investigation requires some deception of participants, the researcher is required to explain and correct any misunderstandings as soon as possible.

4. A subject's right to privacy should never be violated.

5. Harmful or painful procedures imposed on animals must be thoroughly justified in terms of the knowledge to be gained from the study. Prior to conducting studies, approval should be obtained from the host institution (usually a university) and research review committee (usually made up of other psychologists).