AP Psychology Unit 0

Psychological Science Practices: Research Methods and Data Interpretation

Validity

How well an experiment measures or predicts what it’s supposed to

Reliability

The extent to which findings of a research can be replicated

Single-Blind Procedure

Experimental procedure in which the participants are ignorant about whether they have the treatment or placebo

Double-Blind Procedure

Experimental procedure in which both the participants and the research staff are ignorant about whether the participants have the treatment or placebo

Placebo

A pseudo-treatment with no active ingredients; used to counter the placebo effect—experimental results caused by expectations alone

Experimental Group

Group exposed to the treatment (to one version of the IV)

Control Group

Group not exposed to the treatment; serves as comparison for evaluating the effects of the treatment

Theory

Explanation that organizes observations and predicts behavior (explains behaviors)

Hypothesis

A testable prediction (implied by or produced from theory)

Operational Definition

Carefully worded statement of the exact procedures used in a research study (and defining concepts; e.g. defining sleep deprivation)

Overconfidence

Tendency to think we know more than we do

Hindsight Bias

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

Perceiving Patterns in Random Events

Tendency to find patterns in series of unrelated or random events

Measures of Central Tendency

Mean - arithmetic average (can be biased by outliers)

Mode - most frequently occurring data point (bimodal when 2 modes)

Median - middle data point in a distribution (usually unaffected by outliers)

Measures of Variation

Range - difference between highest and lowest data points

Standard Deviation - measure of how much data points deviate from mean (sqrt of variance)

Normal Curve

Symmetrical, bell curve describing data distribution; 68% within 1 std dev, 95% within 2, and 99% within 3

Random Sampling

Method of obtaining a representative sample of the population where every member has an equal chance of being selected; allows conclusions to be generalized to population

Random Assignment

Method of assigning research participants to experimental and control groups in a way that every participant has an equal chance of being selected for each group; controls confounding variables and researcher bias

Naturalistic Observation (Descriptive Research)

Non-experimental technique of observing and recording behavior in naturally occurring situations without manipulation (does not explain behavior)

Case Study (Descriptive Research)

Non-experimental technique in which an individual or group is studied in-depth (not generalizable, expensive, time-consuming, unique cases can be misleading)

Survey (Descriptive Research)

Non-experimental technique for obtaining self-reported attitudes or behaviors of a particular group, usually given to a random sample of the group (susceptible to wording effect, volunteer effect, research bias, sampling bias)

Correlation

Measure of the extent to which two factors vary together; how well one predicts the other; CORRELATION DOES NOT EQUAL/IMPLY CAUSATION

Causation

How one factor affects or leads to another

Correlation Coefficient

Statistical index of relationship between two factors (from -1.00 to +1.00)

Scatterplot

Graphed cluster of dots; shows a visual representation of any correlation between two variables

Illusory Correlation

Perceiving a relationship when none exist or perceiving a stronger-than-actual relationship

Scientific Attitude

Curiosity - open-minded to new ideas and drive to test predictions

Skepticism - not cynical (believing nothing), but not gullible (believing everything)

Humility - awareness of our vulnerability to error and openness to new surprises and perspectives

Independent Variable

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

Dependent Variable

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

Confounding Variables

In an experiment, factors other than those being studied that might influence results

Statistical Significance

Probability of null hypothesis being true (result occurred purely by chance); null hypothesis rejected if p-values—the probability of the result given null hypothesis—is below 5%

Ethical Guidelines for Research

Informed consent - giving participants enough information about a study to enable them to choose whether they wish to participate

Protection from harm - protection from greater-than-usual emotional or physical harm

Confidentiality - information about participants is kept private

Debriefing - post-experimental explanation of a study, including its purpose and any deceptions to participants