Psychology Research Methods and Statistical Concepts Review

critical thinking

The objective analysis and evaluation of an issue in order to form a judgment.

hindsight bias

The tendency to see events as having been predictable after they have already occurred.

peer reviewers

Experts in a field who evaluate the quality and validity of research before publication.

theory

A well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses, and facts.

hypothesis

A testable prediction about the relationship between two or more variables.

falsifiable

The ability of a theory or hypothesis to be disproven by evidence.

operational definition

A statement of the procedures used to define research variables.

replication

The process of repeating a study to see if the original results can be obtained.

case study

An in-depth analysis of a person, group, event, or situation.

naturalistic observation

Observing subjects in their natural environment without interference.

survey

A method of gathering information from a sample of individuals.

social desirability bias

The tendency of respondents to answer questions in a manner that will be viewed favorably by others.

self-report bias

The tendency for individuals to provide inaccurate or false responses to questions about themselves.

sampling bias

A bias that occurs when the sample is not representative of the population from which it was drawn.

random sample

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

population

The entire group of individuals or instances about whom we hope to learn.

correlation

A measure of the relationship between two variables.

correlation coefficient

A numerical index of the degree of relationship between two variables.

variable

Any factor, trait, or condition that can exist in differing amounts or types.

scatterplot

A graphical representation of the relationship between two quantitative variables.

illusory correlation

The perception of a relationship where none exists.

regression toward the mean

The tendency for extreme or unusual scores to fall back toward the average on subsequent measurements.

experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process.

experimental group

The group in an experiment that is exposed to the treatment or independent variable.

control group

The group in an experiment that is not exposed to the treatment and serves as a comparison.

random assignment

The process of assigning participants to the experimental and control groups by chance.

single-blind procedure

An experimental procedure in which both the research participants and the research staff are ignorant about whether the participants have received the treatment or a placebo.

double-blind procedure

An experimental procedure in which both the participants and the staff are unaware of which participants have received the treatment.

placebo effect

The phenomenon in which a patient experiences a perceived improvement in condition due to believing they are receiving treatment.

independent variable

The variable that is manipulated in an experiment.

confounding variable

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

experimenter bias

The influence of the experimenter's expectations on the outcome of the research.

dependent variable

The outcome factor that is measured in an experiment.

validity

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

quantitative research

Research that collects and analyzes numerical data.

qualitative research

Research that collects and analyzes non-numerical data.

informed consent

An ethical principle requiring that research participants be fully informed about the nature of the research and its potential risks.

debriefing

The process of informing participants about the study's purpose and any deceptions that occurred after the study is completed.

descriptive statistics

Statistics that summarize the data collected in a study.

histogram

A graphical representation of the distribution of numerical data.

mode

The value that appears most frequently in a data set.

mean

The average of a set of numbers, calculated by dividing the sum of the values by the number of values.

median

The middle value in a data set when the values are arranged in order.

percentile rank

A measure indicating the value below which a given percentage of observations fall.

skewed distribution

A distribution that is not symmetrical and has a tail on one side.

range

The difference between the highest and lowest values in a data set.

In 1 standard deviation

A statistical term that describes the range within which approximately 68% of the data points fall in a normal distribution.

normal curve

A symmetrical bell-shaped curve that represents the distribution of scores in a population.

inferential statistics

Statistics that allow researchers to make inferences about a population based on a sample.

meta-analysis

A statistical technique for combining the findings from independent studies.

statistical significance

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

effect size

A quantitative measure of the magnitude of a phenomenon.