AP Psych Unit 0 Science Practices

Confirmation Bias

Gather evidence supporting a conclusion while ignoring or not seeking evidence that refutes it.

Hindsight Bias

Believing that we know something only after the event occurs. "I knew it all along."

Overconfidence

Believing that we know more than we do.

The Scientific Method

A systematic process for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge.

Theory

Related hypotheses supported by evidence and may predict many other associated phenomena.

Participant

A person who takes part in a research study.

Hypothesis

A predicted outcome that one can test.

Falsifiable Hypothesis

A hypothesis that can be proven incorrect by an experiment.

Operational Definitions

A description of the variable that enables replication; it usually explains how one measures it.

Replication

Repeating an experiment- is often used to gain more confidence in the initial results.

Case Study

Studying one or a few people in great depth.

Naturalistic Observation

Watch and record everyday behavior in natural settings.

Survey

A study in which researchers select a group of participants from a population and data about or opinions from those participants are collected, measured, and analyzed.

Population

The total number of individuals in a given area.

Sample

A subset of a population that the researcher selects to make inferences about a population.

Random Sample

Every person in a population has the same probability of being selected, which reduces bias and helps make the sample representative of the population.

Representative Sample

Selecting participants so that the sample accurately reflects the entire population.

Convenience Sample

Selecting participants by chance or availability.

Social Desirability Bias

The tendency to give answers based on what is socially acceptable or the perceived desires of the researcher.

Self-Report Bias

A methodological problem occurs when researchers ask people to describe their thoughts, feelings, or behaviors instead of measuring them directly.

Peer Review

The process of submitting academic work to other professionals in the field for critique and evaluation before being published in journals.

Correlation

A relationship between variables or how well they can predict one another; correlation does not necessarily mean causation.

Directionality Problem

When two variables are related but, it is not known which is the cause and which is the effect.

Third Variable Problem

A hidden variable that may be causing the other two.

Correlation Coefficient

A numerical representation of a correlation.

Scatterplot

A graphical representation of a correlation.

Positive Correlation

Both variables rise and fall together.

Negative Correlation

The variables are inversely related. As one rises, the other falls.

Independent Variable (IV)

A variable that a researcher manipulates or controls to determine its effect.

Dependent Variable (DV)

The outcome of the IV.

Extraneous Variables

Variables that are not the IV or DV but may affect the outcome.

Confounding Variables

An extraneous variable that causes systematic variation which makes it difficult to separate from the IV.

Placebo

A medical or psychological intervention or treatment that cannot change something. Ex. A sugar pill instead of a medication.

Placebo Effect

A response to a treatment based on the recipient's expectations. It can confound an experiment.

Single Blind Procedure

Participants are unaware of the experimental conditions.

Double Blind Procedure

Neither the researchers and the participants do not know who received the treatment.

Random Assignment

Participants are placed in groups randomly. Each person has an equal chance of being in any group. Decreases the likelihood of confounding variables.

Experimental Group

Receives the treatment.

Control Group

Does not receive the treatment or gets a placebo.

Quantitative Research

Using numerical measurement.

Likert Scales

An attitude measurement with positive and negative evaluations. Ex. Strongly Disagree, Disagree, Neutral, Agree, Strongly Agree.

Qualitative Research

Using descriptive data without numbers.

Structured Interviews

Questions, wording, and order are predetermined and kept consistent for each participant.

American Psychological Association (APA)

Sets the guidelines for ethical research.

Informed Consent

Prior approval to participate. Often requires the signature of the participants.

Informed Assent

Prior approval to participate by someone not able to give legal consent (under 18 years old).

Debriefing

Explain the true purpose of a study after completion.

Institutional Review Board (IRB)

Must give prior approval to the researchers.

Descriptive Statistics

The main aspects of a data sample without inferring to a larger population. Usually, the mean, median, or mode.

Central Tendency

The middle or center point of a set of scores.

Mean

The average. Sum of all scores divided by the number of scores. Default measurement. Not used when there are extreme outliers and few scores.

Median

The midpoint of scores.

Mode

The most frequently occurring.

Range

Subtract the lowest score from the highest score.

Histogram

A graphical depiction of continuous data. Similar to a bar graph, but with the blocks connected to demonstrate the continuity of the data.

Standard Deviation (SD)

A measure of the variability of scores around the mean. A small SD means the scores are close to the mean. A large SD means they vary from the mean.

Normal Curve

Bell-shaped, symmetrical, the mean, median, and mode are the same, fixed proportional values.

Positive Skew

A few extreme scores towards the high end. Mean is greater than the mode. Ex. A hard test with most students scoring around a 60%, but two students score a 100%.

Negative Skew

A few extreme scores towards the low end. Mean is less than the mode. Ex. It is an easy test, with most students scoring around 95%, but two students fail it with 40%.

Bimodal Distribution

A set of scores with two peaks that values tend to cluster around.

Variation

A measure of the spread of scores within a sample or population.

Inferential Statistics

People use them to determine what can be known about a population from the sample studied.

Statistical Significance

Evaluation of the confidence that the change was not due to chance. Often set at 5%. Also called the p-value. Sample size impacts the significance. The larger the sample, the less likely the findings occurred by chance.

Effect Size

A measure of the magnitude of a relationship between two variables. It allows one to interpret the practical significance of the results.

Meta-analysis

A quantitative study that combines the results of multiple studies on a topic into a single study by combining the effect sizes.