Unit O: An Introduction to Psychological Science Practices

A set of vocabulary flashcards covering key research methods, experimental terms, and statistical concepts from Unit O Review.

critical thinking

Thinking that does not blindly accept arguments and conclusions but instead examines assumptions, appraises the source, discerns hidden bias, evaluates evidence, and assesses conclusions.

hindsight bias

The tendency to believe, after learning an outcome, that one would have overseen it; also known as the $\text{I-knew-it-all-along}$ phenomenon.

peer reviewers

Scientific experts who evaluate a research study's quality, originality, and validity before it is published in a journal.

theory

An explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

hypothesis

A testable prediction, often implied by a theory, designed to be tested.

falsifiable

The requirement that a theory or hypothesis must be capable of being proved wrong; it can be tested and rejected if it is false.

operational definition

A carefully worded statement of the exact procedures or operations used in a research study to define the variables.

replication

Repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding persists.

case study

A descriptive research technique in which one individual or group is studied in depth in the hope of revealing universal principles.

naturalistic observation

A descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

survey

A descriptive technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample.

social desirability bias

The tendency for research participants to respond in ways that are perceived as socially acceptable rather than providing honest answers.

self-report bias

A type of bias that occurs when participants inaccurately or dishonestly report their own behaviors, attitudes, or opinions.

sampling bias

A flawed sampling process that produces an unrepresentative sample of a population.

random sample

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

population

All those in a group being studied, from which samples may be drawn.

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, ranging from $-1.00$ to $+1.00$.

variable

Anything that can vary and is feasible and ethical to measure in a study.

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.

illusory correlation

Perceiving a relationship between variables even when no such relationship exists.

regression toward the mean

The tendency for extreme or unusual scores or events to fall back or regress toward the average.

experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process.

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 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 about whether the research participants have received the treatment or a placebo.

placebo effect

Experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition.

independent variable

In an experiment, the factor that is manipulated; the variable whose effect is being studied.

confounding variable

A factor other than the factor being studied that might influence a study's results.

experimenter bias

A process where the scientists performing the research influence the results in order to portray a certain outcome.

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.

qualitative research

Research that relies on non-numerical data such as descriptions, interviews, and observations to understand concepts.

quantitative research

Research that focuses on quantifying the collection and analysis of numerical data.

informed consent

Giving potential participants enough information about a study to enable them to choose whether they wish to participate.

debriefing

The post-experimental 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; includes 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 ($n$).

median

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

percentile rank

The percentage of scores in a distribution that a specific score is greater than or equal to.

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; about $68\%$ of scores fall within one standard deviation of the mean.

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 an obtained result occurred by chance.

effect size

A measure of the magnitude of an experimental result or the strength of the relationship between variables.