Studied by 10 people
Critical Thinking
Thinking that examines assumptions, appraises sources, discerns hidden biases, evaluates evidence, and assesses conclusions rather than automatically accepting arguments.
Hindsight Bias
The tendency to believe, after learning an outcome, that one would have foreseen it; also known as the I-knew-it-all-along phenomenon.
Peer Reviewers
Scientific experts who evaluate a research article’s theory, originality, and accuracy.
Theory
An explanation that organizes observations and predicts behaviors or events using an integrated set of principles.
Falsifiable
The possibility that an idea, hypothesis, or theory can be disproven by observation or experiment.
Hypothesis
A testable prediction often implied by a theory.
Operational Definition
A carefully worded statement of the exact procedures used in a research study, such as defining human intelligence based on what an intelligence test measures.
Replication
Repeating the essence of a research study with different participants in different situations to see if the basic finding can be reproduced.
Case Study
A non-experimental technique studying one individual or group in depth to reveal universal principles.
Naturalistic Observation
A non-experimental technique of observing and recording behavior in naturally occurring situations without manipulation.
Survey
A non-experimental technique for obtaining self-reported attitudes or behaviors from a representative, random sample of a group.
Social Desirability Bias
Bias arising from people responding in ways they believe a researcher expects or wishes.
Self-Report Bias
Bias that occurs when people inaccurately report their behavior.
Sampling Bias
A flawed sampling process that produces an unrepresentative sample.
Random Sample
A sample that fairly represents a population because each member has an equal chance of inclusion.
Population
All individuals in a group being studied from which samples may be drawn, not referring to a country’s entire population except in national studies.
correlation
a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.
correlation coefficient
a statistical index of the relationship between two things (from −1.00 to +1.00).
variable
anything that can vary and is feasible and ethical to measure.
scatterplot
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 (little scatter indicates high correlation).
illusory correlation
perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship.
regression toward the mean
the tendency for extreme or unusual scores or events to fall back (regress) toward the average.
experiment
a research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant factors.
experimental group
in an experiment, the group exposed to the treatment, that is, to one version of the independent variable.
control group
in an experiment, the group 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 groups by chance, thus minimizing preexisting differences between the different groups.
single-blind procedure
an experimental procedure in which the research participants are ignorant (blind) about whether they have received the treatment or a placebo.
double-blind procedure
an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.
placebo effect
experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.
independent variable
in an experiment, the factor that is manipulated; the variable whose effect is being studied.
confounding variable
in an experiment, a factor other than the factor being studied that might influence a study’s results.
experimenter bias
bias caused when researchers may unintentionally influence results to confirm their own beliefs.
dependent variable
in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated.
validity
the extent to which a test or experiment measures or predicts what it is supposed to. (See also predictive validity.)
quantitative research
a research method that relies on quantifiable, numerical data.
qualitative research
a research method that relies on in-depth, narrative data that are not translated into numbers.
informed consent
giving potential participants enough information about a study to enable them to choose whether they wish to participate.
debriefing
the postexperimental explanation of a study, including its purpose and any deceptions, to its participants.
descriptive statistics
numerical data used to measure and describe characteristics of groups; include measures of central tendency and measures of variation.
histogram
a bar graph depicting a frequency distribution.
mode
the most frequently occurring score(s) in a distribution.
mean
the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores.
median
the middle score in a distribution; half the scores are above it and half are below it.
percentile rank
the percentage of scores that are lower than a given score.
skewed distribution
a representation of scores that lack symmetry around their average value.
range
the difference between the highest and lowest scores in a distribution.
standard deviation
a computed measure of how much scores vary around the mean score.
normal curve
a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer scores lie near the extremes. (Also called a normal distribution.)
inferential statistics
numerical data that allow one to generalize — to infer from sample data the probability of something being true of a population.
meta-analysis
a statistical procedure for analyzing the results of multiple studies to reach an overall conclusion.
statistical significance
a statistical statement of how likely it is that a result (such as a difference between samples) occurred by chance, assuming there is no difference between the populations being studied.
effect size
the strength of the relationship between two variables. The larger the effect size, the more one variable can be explained by the other.
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