AP Psychology Ch. 3: Research Methods

experiment

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

correlation coefficient

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

median

The middle number in a set of numbers that are listed in order

mode

The number that occurs most often in a set of data

false consensus

a belief that others share the same opinion about something, when actually most don't.

causation

a cause and effect relationship in which one variable controls the changes in another variable.

standard deviation

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

experimenter bias

a confounding variable that occurs when an experimenter unintentionally encourages participants to respond in a way that supports the hypothesis.

positively skewed distribution

a data distribution with a few very high scores.

negatively skewed distribution

a data distribution with a few very low scores.

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.

normal distribution

a mathematically defined frequency distribution in which most measurements are concentrated around the middle (bell curve).

correlation

a measure of the relationship between two variables.

scientific method

a method of investigation involving observation and theory to test scientific hypotheses.

random sample

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

operational definition

a statement of the procedures used to define research variables.

statistical significance

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

survey

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

hypothesis

a testable prediction, often implied by a theory.

population

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

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.

theory

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

intuition

an innate belief about something, often without conscious consideration.

case study

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

variable

anything that can vary among subjects (age, gender, health, etc).

random assignment

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

scientific attitude

curiosity or inquisitiveness, objectivity, open-mindedness, perseverance, humility, ability to accept failure, and skepticism.

standardization

defining meaningful scores by comparison with the performance of a pretested standardization group.

placebo effect

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

debriefing

giving participants in a research study a complete explanation of the study after the study is completed.

APA ethical guidelines (animal reasearch)

having a clear scientific purpose, caring for and housing animals in a humane way, acquiring animal subjects legally, designing experimental procedures that employ the least amount of suffering feasible.

confounding variable

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

the barnum effect

individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people (example: horoscopes).

APA ethical guidelines (human research)

no coercion (voluntary); informed consent; anonymity; little to no risk; debriefing.

naturalistic observation

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

overconfidence

our tendency to believe we will perform better than we actually do.

basic research

pure science that aims to increase the scientific knowledge base; cannot be immediately used.

replication

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.

applied research

scientific study that aims to solve practical problems; can be immediately used.

mean

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

range

the difference between the highest and lowest scores in a distribution

culture

the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next

independent variable

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

validity

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

reliability

the extent to which a test yields consistent results, as assessed by the consistency of scores on two halves of the test, on alternate forms of the test, or on retesting.

control group (control condition)

the group (condition) in an experiment that contrasts with the experimental condition and serves as a comparison for evaluating the effect of the treatment

experimental group (experiemental condition)

the group (condition) in an experiment that exposes participants to the treatment, that is, to one version of the independent variable.

dependent variable

the outcome factor; the variable that may change in response to manipulations of the independent variable.

illusory correlation

the perception of a relationship where none exists.

Hawthorne effect

the tendency of people to behave differently if they know that they are being observed.

hindsight bias

the tendency to believe, after learning an outcome, that one would have foreseen it

critical thinking

thinking that does not blindly accept arguments and conclusions, rather, it examines assumptions, discerns hidden values, evaluates evidence, and assesses conclusions.