Hindsight Bias

I-knew-it-all-along-phenomenon

People believe that they knew something all along after an event happens .

People believe that they knew something all along after an event happens .

Critical Thinking

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

Theory

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

Hypothesis

A testable prediction often implied by a theory.

Operational Definition

Statement of the procedures (operations) used to define research variables.

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.

Survey

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

Population

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

Random Sample

A 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

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

Correlation Coefficient

A statistical index of the relationship of two things.

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.

Illusory Correlation

The perception of a relationship where none exists.

Experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental processes. By random assignment of participants, the experimenter aims to control other relevant factors.

Random Assignment

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

Double-Blind Procedure

An experiment procedure in which both the research participants and 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.

Experimental Group

The group that is exposed to the treatment, that is, to one version of the independent variable.

Independent Variable

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

Confounding (Third) Variable

A factor other than the independent variable that might produce an effect in an experiment.

Dependent Variable

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

Mean

The arithmetic average of a distribution, obtained by adding the score s 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.

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 described the distribution of many types of data; most scores fall towards the mean and few near the extremes.

Statistical Significance

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

Culture

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

Informed Consent

An ethical principle that research participants be told enough to enable them to choose whether they with to participate.

Debriefing

The post experimental explanation of a study, including its purpose and any deceptions to its participants.

case study

an observation technique in which one person is studied in depth in hope of revealing universal principals

control group

in an experiment the group that is not exposed to the treatment , serves as a comparison for the experimental group

mode

the most frequently occurring scores in a distribution