Unit 0: Research Methods and Data Interpretation.

Critical Thinking

Thinking that does not automatically accept arguments and conclusions. Examines assumptions, appraises the source, discerns hidden biases, evaluates evidence, and assesses conclusions.

Hindsight Bias

Tendency to believe, after learning an outcome, that one would have foreseen it (“I knew it all along”).

Peer reviewers

Experts who evaluate research before publication to ensure accuracy and quality.

Theory

Explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

Hypothesis

A testable prediction, often implied by a theory.

Falsifiable

Possibility that an idea, hypothesis, or theory can be disproven by observation or experiment.

Operational Definition

A clear and specific statement that defines how a variable will be measured or observed in research.

Replication

Repeating the essence of a research study, usually with different participants in different situations to determine the reliability and validity of the original findings.

Case Study

A non-experimental technique in which one individual or group is studied in depth in the hope of revealing universal principles.

Naturalistic Observation

A non-experimental technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

Survey

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

Social desirability bias

Bias from people’s responding in ways they presume a researcher expert or wishes.

Self-Report bias

Bias when people report their behavior inaccurately

Sampling Bias

A flawed sampling process produces an unrepresentative sample

Random Sample

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

Population

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

Correlation

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

Correlation coefficient

A statistical index of the relationship between two variables (from -1.00 to +1.00).

Variable

Anything that can vary and is feasible and ethical to measure.

Scatterplot

Graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the relationship between the two variables. The amount of scatter suggests the strength of the correlation.

Illusory correlation

Perceiving a relationship where none exists, or perceiving a stronger than actual relationship.

Regression toward the mean

The tendency for the extreme or unusual scores or events to fall back (regress) toward the average.

Experiment

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

Experimental group

In an experiment, the group exposed to the treatment—this 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 the 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.

Single-blind procedure

An experimental procedure in which the research participants are ignorant (blind) about whether they have received the treatment or a placebo

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. Common in drug 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.

Independent Variable

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

Confounding variable

In an experiment, a factor other than the factor being studied that might influence a study’s results.

Experimenter Bias

Bias caused when researchers may unintentionally influence results to confirm their own beliefs.

Dependent variable

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

Validity

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

Quantitative research

A research method that relies on quantifiable, numerical data

Qualitative research

A research method that relies on in-depth narrative data that are not translated into numbers.

Informed consent

Giving potential participants enough information about a study to enable them to choose whether they wish to participate.

Debriefing

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

Descriptive statistics

Numerical data used to measure and describe characteristics of groups; include measures of central tendency and measures of variations.

Histogram

A bar graph depicting a frequency distribution.

Mode

The most frequently occurring score(s) in a distribution.

Mean

Arithmetic average of a distribution, obtained by adding the scores and then diving by the number of scores.

Median

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

Percentile rank

The percentage of scores that are lower than a given score

Skewed distribution

A representation of scores that lack symmetry around their average value.

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 describes the distribution of many types of data; most scores fall near the mean and fewer and fewer scores lie near the extremes.

Inferential statistics

Numerical data that allows one to generalize— to infer from sample data the probability of something being true of a population.

Meta-analysis

A statistical procedure for analyzing the results of multiple studies to reach an overall conclusion.

Statistical significance

A statistical statement of how likely it is that a result occurred by chance, assuming there is no difference between populations being studied.

Effect size

The strength of the relationship between two variables. The larger the effect size, the more one variable can be explained by the other.