Research Methods: Thinking Critically with Psychological Science

hindsight bias
the tendency to believe, after learning an outcome, that one would have foreseen it. (I-knew-it-all-along phenomenon)

critical thinking
thinking that does not blindly accept arguments and conclusions. Rather, it examines assumption, discerns hidden values, evaluates evidences, and assesses conclusions

an explanations using an integrated set of principles that organizes and predicts observations.

a testable prediction, often implied by a theory.

operational definition
a statement of procedures (operations) used to define research variables. (ex: memory may be defined as “number of words correctly recalled from a list”).

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances.

case study
an observation technique in which one person is studied in depth in the hope of revealing universal principles.

a technique for ascertaining the self-reported attitudes or behaviors of people, usually by questioning a representative, random sample of them.

false consensus effect
the tendency to overestimate the extent to which others share our beliefs and behaviors.

all the cases in a group, from which samples may be drawn for a study.

random sample
sample that fairly represents a population because each member has an equal chance of inclusion.

naturalistic observation
observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

correlation coefficient
a statistical measure of the extent to which two factors vary together, and thus of how well either factor predicts the other

a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation.

illusory correlation
the perception of a relationship where none exists; the basis for many superstitions

a research method in which an investigator manipulates one of more factors (independent variables) to observe the effect on some behavior or mental process (dependent variable). By random assignment of participants, the experiment controls other relevant factors.

double-blind procedure
an experimental procedure in which both the research staff are ignorant (blind) about whether the research participants have received the treatment or placebo.

placebo effect
experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance of condition, which is assumed to be an active agent.

hawthorne effect
tendency of some people to work harder and perform better when they are participants in an experiment. Individuals may change their behavior due to the attention they are receiving from researchers rather than because of any manipulation of independent variables.

experimental group
A subject or group of subjects in an experiment that is exposed to the factor or condition being tested.

control group
the condition of an experiment that contrasts with the experimental condition and serves as a comparison for evaluating the effect of the treatment., In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

random assignment
assigning participants to experimental and control conditions by chance, thus minimizing preexisting differences between those assigned to the different groups.

independent variable
the experimental factor that is manipulated; the variable whose effect is being studied.

dependent variable
the experimental factor – in psychology, the behavior or mental process – that is being measured; the variable that may change in response to manipulations of the independent variable.

descriptive statistics
Statistics used to describe only the observed group or sample from which they were derived; summary statistics such as percent, averages, and measures of variability that are computed on a particular group of individuals.

inferential statistics
numerical methods used to determine whether research data support a hypothesis or whether results were due to chance (e.g. p-value)

the most frequently occurring score in a distribution.

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.

the middle score in a distribution; half the scores are above it and half are below it.

the difference between the highest and the lowest scores in a distribution.

standard deviation
a computed measure of how much scores vary around the mean score.

statistical significance
a statistical statement of how likely it is that an obtained result occurred by chance.

APA Ethical Guidelines
these rules specify that researchers avoid procedures that might cause serious physical or mental harm to human subjects, protect confidentiality of the data, respect a subject’s right to refuse at any time during the study; includes Informed Consent, Freedom to Withdraw, Debriefing, No Harm, and Confidentiality

the tendency to be more confident than correct—to overestimate the accuracy of one’s beliefs and judgments.

confirmation bias
a tendency to search for information that supports our preconceptions and to ignore or distort contradictory evidence

wording effects
when a specific word used in a question affects how respondents answer the question or the order of the questions

the method used to observe and record behavior without manipulation (survey, case study, naturalistic observation)

The probability level which forms basis for deciding if results are statistically significant (not due to chance).

items (often people) selected at random from a population and used to test hypotheses about the population

confounding variable
in an experiment, a variable, other than the independent variable, that could influence the dependent variable

giving participants in a research study a complete explanation of the study after the study is completed; required by APA ethics guidelines

informed consent
agreement to participate in psychology research, after being informed of the dangers and benefits of the research

the extent to which a study’s findings can be reasonably assumed to apply to the study population (not just the sample); enhanced by having larger, random samples and large differences between (experimental and control) groups

social desirability bias
A tendency to give socially approved answers to questions about oneself; a potential challenge in surveys involving self-report

sampling bias
A problem that occurs when a sample is not representative of the population from which it is drawn.

A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

the extent to which a test or experiment measures or predicts what it is supposed to

skewed distribution
a representation of scores that lack symmetry around their average value

A graph of vertical bars representing the frequency distribution of a set of data.

normal curve
the symmetrical bell-shaped curve that describes the distribution of many physical and psychological attributes. Most scores fall near the average, and fewer and fewer scores lie near the extremes.

institutional review board (IRB)
A committee organized by a university or other research institution that approves, monitors, and reviews all research that involves human subjects. Its main purpose is to ensure compliance with ethics standards.

Researchers sometimes need to keep details of a research design hidden from participants (or intentionally mislead them about the study’s true purpose). Note: must be corrected during debriefing