Barron's AP Psychology 685 Terms and Definitions Study Guide
Hindsight bias The tendency to believe, after learning an outcome, that one would have predicted
it beforehand; the 'I knew it all along' phenomenon.
Confirmation bias The tendency to search for, interpret, and recall information in a way that confirms
one's preexisting beliefs or hypotheses.
Overconfidence The tendency to overestimate the accuracy of one's own knowledge and judgments.
Quantitative research Research that collects and analyzes numerical data to identify patterns, test
hypotheses, and make predictions.
Qualitative research Research that collects non-numerical data (such as words, descriptions, and
observations) to understand behavior and experiences in depth.
Hypothesis A testable prediction about the relationship between two or more variables, derived
from a theory.
Dependent variable The outcome variable that is measured in an experiment; the variable that may
change as a result of manipulating the independent variable.
Independent variable The variable that is manipulated by the experimenter to observe its effect on the
dependent variable.
Falsifiable Capable of being disproved by evidence; a key criterion for a scientific hypothesis or
theory.
Operational definitions Precise descriptions of how variables will be measured or manipulated in a specific
study.
Replicated When a study is repeated by other researchers and produces the same results,
increasing confidence in the original findings.
Sample A subset of a population selected to participate in a research study.
Population The entire group of individuals that a researcher wants to draw conclusions about.
Representative sample A sample that accurately reflects the characteristics of the population from which it
was drawn.
Random sampling A sampling method in which every member of the population has an equal chance
of being selected, increasing representativeness.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Convenience sampling A sampling method in which participants are chosen based on their easy availability,
which may limit generalizability.
Generalize To apply findings from a sample to the broader population.
Stratified sampling A sampling method in which the population is divided into subgroups and
participants are randomly selected from each subgroup in proportion to their
representation in the population.
Confounding variables Factors other than the independent variable that may influence the dependent
variable, potentially distorting results.
Random assignment The process of randomly placing participants into experimental or control groups,
helping to equalize group differences and control for confounding variables.
Experimenter bias When a researcher's expectations or beliefs unconsciously influence how they
conduct a study or interpret results.
Double-blind study A research design in which neither the participants nor the researchers interacting
with them know who is in the experimental or control group, reducing bias.
Single-blind study A research design in which participants do not know whether they are in the
experimental or control group, but the researchers do.
Social desirability bias The tendency for research participants to respond in ways they believe will be
viewed favorably by others, rather than answering honestly.
Experimental group The group in an experiment that receives the treatment or manipulation of the
independent variable.
Control group The group in an experiment that does not receive the treatment and serves as a
baseline for comparison.
Placebo method Giving participants in the control group a fake treatment that appears identical to the
real treatment, used to control for the placebo effect.
Placebo effect A measurable improvement in outcomes resulting from a participant's belief that
they are receiving an effective treatment, even when the treatment is inert.
Positive correlation A relationship between two variables in which both increase or decrease together.
Negative correlation A relationship between two variables in which one increases as the other
decreases.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Ex post facto study A research design in which the researcher studies pre-existing differences in groups
rather than manipulating a variable; participants are assigned based on
characteristics they already possess.
Likert scales A rating scale used in surveys in which respondents indicate their level of
agreement with a statement, typically ranging from 'strongly disagree' to 'strongly
agree.'
Directionality problem In correlational research, the difficulty of determining which variable causes the
other; a limitation of correlational studies.
Third variable An unmeasured variable that may be responsible for the observed correlation
between two other variables.
Naturalistic observation A descriptive research method in which behavior is observed and recorded in a
natural setting without interference from the researcher.
Structured interview A research method in which each participant is asked the same predetermined set
of questions in the same order.
Case study An in-depth investigation of a single individual, group, or event, often used to
explore rare or unusual phenomena.
Central tendency A statistical measure that represents the center or typical value of a data set,
including mean, median, and mode.
Mean The arithmetic average of a set of scores, calculated by dividing the sum of all
scores by the number of scores.
Median The middle score in a rank-ordered set of data; half the scores fall above and half
below this value.
Mode The most frequently occurring score or value in a data set.
Bimodal A distribution with two modes, or two frequently occurring scores.
Positively skewed A distribution in which the tail extends toward higher values (the right), pulling the
mean above the median.
Negatively skewed A distribution in which the tail extends toward lower values (the left), pulling the
mean below the median.
Range The difference between the highest and lowest scores in a data set; a measure of
variability.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Variance The average of the squared differences from the mean, indicating how spread out
the scores are in a data set.
Standard deviation A statistic that measures the average distance of scores from the mean; a widely
used measure of variability.
Normal curve A symmetrical, bell-shaped curve that describes the distribution of many
psychological and biological variables, with most scores clustering near the mean.
Percentiles A score indicating the percentage of data points that fall at or below a given value.
Correlation A statistical relationship between two variables; correlations range from -1.00 to
+1.00 and do not imply causation.
Correlation coefficient A numerical index (ranging from -1.00 to +1.00) indicating the strength and direction
of the relationship between two variables.
Scatterplot A graph that displays the relationship between two variables by plotting each data
point as a dot on a two-dimensional axis.
Statistically significant A result that is unlikely to be due to chance alone, typically indicated by a p-value
below 0.05, suggesting the result reflects a true effect.
Effect size A quantitative measure of the magnitude or practical significance of an experimental
result, independent of sample size.
Replication crisis A methodological problem in psychology and other sciences in which many
published research findings fail to be replicated by other researchers.
Meta-analysis A statistical technique that combines and analyzes data from multiple studies on a
topic to draw more reliable conclusions.
Peer review The process by which a study is evaluated by other experts in the field before it is
published, helping ensure quality and validity.
No coercion An ethical principle requiring that research participants must not be pressured or
forced to participate; participation must be voluntary.
Informed consent An ethical requirement that participants be told enough about a study to decide
voluntarily whether to participate.
Deception Withholding information from or misleading participants about the true nature of a
study; permitted only when necessary and followed by debriefing.
Grade A+ | Updated
Hindsight bias The tendency to believe, after learning an outcome, that one would have predicted
it beforehand; the 'I knew it all along' phenomenon.
Confirmation bias The tendency to search for, interpret, and recall information in a way that confirms
one's preexisting beliefs or hypotheses.
Overconfidence The tendency to overestimate the accuracy of one's own knowledge and judgments.
Quantitative research Research that collects and analyzes numerical data to identify patterns, test
hypotheses, and make predictions.
Qualitative research Research that collects non-numerical data (such as words, descriptions, and
observations) to understand behavior and experiences in depth.
Hypothesis A testable prediction about the relationship between two or more variables, derived
from a theory.
Dependent variable The outcome variable that is measured in an experiment; the variable that may
change as a result of manipulating the independent variable.
Independent variable The variable that is manipulated by the experimenter to observe its effect on the
dependent variable.
Falsifiable Capable of being disproved by evidence; a key criterion for a scientific hypothesis or
theory.
Operational definitions Precise descriptions of how variables will be measured or manipulated in a specific
study.
Replicated When a study is repeated by other researchers and produces the same results,
increasing confidence in the original findings.
Sample A subset of a population selected to participate in a research study.
Population The entire group of individuals that a researcher wants to draw conclusions about.
Representative sample A sample that accurately reflects the characteristics of the population from which it
was drawn.
Random sampling A sampling method in which every member of the population has an equal chance
of being selected, increasing representativeness.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Convenience sampling A sampling method in which participants are chosen based on their easy availability,
which may limit generalizability.
Generalize To apply findings from a sample to the broader population.
Stratified sampling A sampling method in which the population is divided into subgroups and
participants are randomly selected from each subgroup in proportion to their
representation in the population.
Confounding variables Factors other than the independent variable that may influence the dependent
variable, potentially distorting results.
Random assignment The process of randomly placing participants into experimental or control groups,
helping to equalize group differences and control for confounding variables.
Experimenter bias When a researcher's expectations or beliefs unconsciously influence how they
conduct a study or interpret results.
Double-blind study A research design in which neither the participants nor the researchers interacting
with them know who is in the experimental or control group, reducing bias.
Single-blind study A research design in which participants do not know whether they are in the
experimental or control group, but the researchers do.
Social desirability bias The tendency for research participants to respond in ways they believe will be
viewed favorably by others, rather than answering honestly.
Experimental group The group in an experiment that receives the treatment or manipulation of the
independent variable.
Control group The group in an experiment that does not receive the treatment and serves as a
baseline for comparison.
Placebo method Giving participants in the control group a fake treatment that appears identical to the
real treatment, used to control for the placebo effect.
Placebo effect A measurable improvement in outcomes resulting from a participant's belief that
they are receiving an effective treatment, even when the treatment is inert.
Positive correlation A relationship between two variables in which both increase or decrease together.
Negative correlation A relationship between two variables in which one increases as the other
decreases.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Ex post facto study A research design in which the researcher studies pre-existing differences in groups
rather than manipulating a variable; participants are assigned based on
characteristics they already possess.
Likert scales A rating scale used in surveys in which respondents indicate their level of
agreement with a statement, typically ranging from 'strongly disagree' to 'strongly
agree.'
Directionality problem In correlational research, the difficulty of determining which variable causes the
other; a limitation of correlational studies.
Third variable An unmeasured variable that may be responsible for the observed correlation
between two other variables.
Naturalistic observation A descriptive research method in which behavior is observed and recorded in a
natural setting without interference from the researcher.
Structured interview A research method in which each participant is asked the same predetermined set
of questions in the same order.
Case study An in-depth investigation of a single individual, group, or event, often used to
explore rare or unusual phenomena.
Central tendency A statistical measure that represents the center or typical value of a data set,
including mean, median, and mode.
Mean The arithmetic average of a set of scores, calculated by dividing the sum of all
scores by the number of scores.
Median The middle score in a rank-ordered set of data; half the scores fall above and half
below this value.
Mode The most frequently occurring score or value in a data set.
Bimodal A distribution with two modes, or two frequently occurring scores.
Positively skewed A distribution in which the tail extends toward higher values (the right), pulling the
mean above the median.
Negatively skewed A distribution in which the tail extends toward lower values (the left), pulling the
mean below the median.
Range The difference between the highest and lowest scores in a data set; a measure of
variability.
Grade A+ | Updated
, Barron's AP Psychology 685 Terms and Definitions Study Guide
Variance The average of the squared differences from the mean, indicating how spread out
the scores are in a data set.
Standard deviation A statistic that measures the average distance of scores from the mean; a widely
used measure of variability.
Normal curve A symmetrical, bell-shaped curve that describes the distribution of many
psychological and biological variables, with most scores clustering near the mean.
Percentiles A score indicating the percentage of data points that fall at or below a given value.
Correlation A statistical relationship between two variables; correlations range from -1.00 to
+1.00 and do not imply causation.
Correlation coefficient A numerical index (ranging from -1.00 to +1.00) indicating the strength and direction
of the relationship between two variables.
Scatterplot A graph that displays the relationship between two variables by plotting each data
point as a dot on a two-dimensional axis.
Statistically significant A result that is unlikely to be due to chance alone, typically indicated by a p-value
below 0.05, suggesting the result reflects a true effect.
Effect size A quantitative measure of the magnitude or practical significance of an experimental
result, independent of sample size.
Replication crisis A methodological problem in psychology and other sciences in which many
published research findings fail to be replicated by other researchers.
Meta-analysis A statistical technique that combines and analyzes data from multiple studies on a
topic to draw more reliable conclusions.
Peer review The process by which a study is evaluated by other experts in the field before it is
published, helping ensure quality and validity.
No coercion An ethical principle requiring that research participants must not be pressured or
forced to participate; participation must be voluntary.
Informed consent An ethical requirement that participants be told enough about a study to decide
voluntarily whether to participate.
Deception Withholding information from or misleading participants about the true nature of a
study; permitted only when necessary and followed by debriefing.
Grade A+ | Updated
