AP Psych - Unit 2: Research Methods

Covers content from textbook and lesson slides. Modules 4 to 8

Hindsight Bias

The tendency to believe, after learning an outcome, that one would have foreseen it (aka the I-knew-it-all-along phenomenon)

Overconfidence

The tendency to think we know more than we do and to exaggerate the correctness or accuracy of our beliefs and predictions

Perceiving Order in Random Events

In our natural eagerness to make sense of an unpredictable world, we are prone to perceive patterns, even when there might not be any

Theory

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

Part of the scientific method, explains behaviors or events by offer ideas that organize observations

Hypothesis

A testable prediction, often implied by a theory, part of the scientific method

Operational Definition

A carefully worded statement of the exact procedures (operations) used in a research study; precise measurements of concepts, part of the scientific method

Replication

Repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding can be reproduced; others can repeat the experiment, part of the scientific method

Descriptive Methods

Describe behaviours, often by using case studies, surveys, or naturalistic observations; a way to test hypotheses and refine theories

Correlational Methods

Associate different factors, or variables; a way to test hypotheses and refine theories

Experimental Methods

Manipulate variables to discover their effects; a way to test hypotheses and refine theories

Variable

Anything that can vary and is feasible and ethical to measure; refers to anything that contributes to a result

Case Study

A descriptive 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 behaviour in naturally occurring situations without trying to manipulate or control the situation; recording the natural behaviour of many individuals

• Does not explain behavior but rather describes it

• Agreement between the observers (called interrater reliability) is crucial

• You must blend in

Survey

A descriptive technique for obtaining the self-reported attitudes or behaviours of a particular group, usually by questioning a representative, random sample of the group; asking people questions

Representative Sample

A subset of a population that seeks to accurately reflect the characteristics of the larger group; has the same distribution of demographic qualities in it as the population as a whole.

Hawthorne Effect

When subjects of an experimental study attempt to change or improve their behavior simply because it is being evaluated or studied; Sometimes just knowing you are being observed can alter behaviour

Wording Effect

The effect that subtle changes in the words or order of words can have on a study participant; Subtle changes in the wording of questions can have major effects

Random Sample

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

Every person in the entire group has an equal chance of participating, typically generates a representative sample

Sampling Bias

A flawed sampling process that produces an unrepresentative sample

Population

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

*(except for national studies, this does not refer to a country’s whole population)

Correlation

Correlation does not equal causation

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

• the degree to which two variables are related/change together, and how well one predicts the other

Positive Correlation

When two factors increase or decrease together (move in tandem)

Negative Correlation

When one variable increases as the other decreases

Association

A co-occurrence of two events, factors, characteristics, or activities such that when one happens, the other is likely to occur as well

• many statistics measure this

• correlations do not show causation

• cause, effect and correlation

Correlation Coefficient

A statistical index of the relationship between two things/variables (from -1.00 to +1.00); describes the strength and direction of a relationship between two variables

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 (little scatter indicates high correlation)

Illusory Correlation

Perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship; are random events that we notice and falsely assume are related

Regression Toward the Mean

The tendency for extreme or unusual scores or events to fall back (regress) toward the average; extraordinary happenings tend to be followed by more ordinary ones

Experiment

A research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant variables; manipulating one or more variables of interest and controlling other variables

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

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; used to avoid the placebo effect and researcher or subject bias

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

Independent Variable

In an experiment, the factor that is manipulated; the variable whose effect is being studied; is the factor manipulated to study its effect

Dependent Variable

In an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated

Is measured to discover any changes occurring in response to the manipulation of the independent variable.

Confounding Variable

A factor other than the factor being studied (independent variable) that might influence or produce an effect in an experiment and results

Validity

The extent to which a test or experiment measures or predicts what it is supposed to; an experiment has this if it measures what it is supposed to measure.

Informed Consent

The ethical principal of giving potential participants enough information about a study to enable them to choose whether they wish to participate

Debriefing

The postexperimental explanation of a study, including its purpose and any deceptions, to its participants; when temporary deception is necessary to the research, it must be fully explained at the conclusion of the experiment.

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; The mathematical average of a set of numbers

Median

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

Skewed Distribution

A representation of scores that lack symmetry around their average value; most of the scores or data fall on one side of the scale and there are very few scores on the other side

When one data point is extremely different from the others, this is called an outlier and can skew the results.

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 (aka Normal Distribution)

A symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (about 68 percent fall within one standard deviation of it) and fewer and fewer near the extremes

Inferential Statistics

Numerical data that allow one to generalize--to infer from sample data the probability of something being true of a population

Statistical Significance

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

Bimodal Distribution

Two different modes, distinct peaks in probability density

Null Hypothesis

Averages based on more cases, of course, will be more reliable. Psychologists typically do not interpret a difference as meaningful unless the odds of it occurring by chance are less than 5%

Group Matching

Refers to a technique used in experimental research where the participants are paired based on specific characteristics (variables) they “match on”, and then divided into groups (conditions).

The purpose of this technique is to reduce the chances of individual differences skewing the obtained results; attempts to use data that has been collected previously

Counterbalancing

When the participant sample is divided in half, with one half completing the two conditions in one order and the other half completing the conditions in the reverse order

Positively Skewed Distribution

A distribution where the data's mean, median, and mode are greater than zero. It indicates that the data is concentrated more toward one side of the scale, with a long tail on the right side

Negatively Skewed Distribution

A longer or fatter tail on the left side of the distribution