Research Methods in Psychology

• Cause and effect
– With an experiment, we can determine cause and effect because we are systematically manipulating variables
– Hypothesis-what do we think will happen in the study?
– Independent variable(s):
– Dependent variable(s):

• Operational definitions-
– What do you mean by the I.V.?
– What do you mean by the D.V.?
– You need to define them so people who read your study know what you are talking about

• Subjects:
– Population
– Sample - #s
– Random Assignment
– Experimental Group
– Control Group

• Extraneous vs. Confounding variables
– Extraneous –
– Confounding –

• 1. Internal
– The problem with internal validity is that it becomes very difficult to generalize the results to the rest of the population. (This can also be a problem with case studies).
• 2. External validity-

• 3. Sampling bias -
• You need to draw a large enough sample to represent the population under study and then utilize random sampling

• 4. Placebo effects –
• Simply placing something in one’s mouth may cause one to experience a placebo effect
• Placebo effects can ruin the experiment because you cannot tell if the drug actually had an effect on the subject or not.

• 5. Distortion of self-report-Occurs when interview and surveys are given. The subject may lie in giving their answers (or just stretch the truth). Can happen in one of two ways:
• A. Social desirability-
• B. Response set-
(Ex- when people agree with or disagree with everything on the survey. Most surveys are set up to elicit positive/negative answers or so that different choices should be made.

• 6. Experimenter bias -
• The best way to overcome this is to do a double-blind study, in which the experimenter does not know which subjects are in which groups

• In order to study development of human beings, we use several different designs:
– 1. Cross-sectional
– 2. Longitudinal
– 3. Sequential

• 1. Naturalistic Observation
– Pros –
– Cons –

• 2. Laboratory Experiment
– Pros –
– Cons –

• 3. Surveys
– Pros –
– Cons –

• 4. Interviews
– Pros –
– Cons –

• 5. Case Study
– Pros –
– Cons –

• 1. Subject participation – voluntary
– Should not be forced or feel pressured
– Should be informed of any factor of research that might make them decide not to participate
– Should be allowed to end participation at any time and still get paid (if they are getting paid)

• 2. Subjects are not to be harmed in any way
– Protect from psychological and physical harm
– Studies that may only effect one’s emotions in a slight way are acceptable

• 3. Deception of participants – Is it okay?
– Should be done to inform participants
– Debriefing of subject is usually necessary

• 4. Right to privacy should not be violated
– Don’t give out information on your subjects
– If data regarding subjects will be released, subjects must be informed and consent must be obtained

• 5. Can we cause them harm?
– Yes to animals – but you must be able to justify it
– Animals should be maintained in a manner that is considered decent treatment

• 6. Approval must be obtained from the institution that the researcher works for
– Research must be reported in an ethical fashion
– Research should be reported as soon as possible for verification

• Mean-Average of all the data
• Mode-# that appears most often. You may have a bimodal distribution which means that two #’s appear the same # of times and are the most frequent #’s in the data set.
• Median-# in the middle
• Range – subtract the lowest # from the highest #

• While experiments tell us about cause and effect,
• Usually after the fact
– correlational studies do NOT tell about causation
• Often cannot experiment on humans
– they ONLY tell us if there is a relationship
• Follow-up may be experiment with animals

• Look for:
– Positive vs. negative relationships
– Strength of the number

• +1 –
• +.7-.9 –
• +.4-.6 –
• +.1-.3 –
• 0 –