Scientific Foundations and Statistical Methods in Psychology
Foundations of Scientific Inquiry in Psychology
Critical Thinking: This involves the rigorous process of evaluating evidence, appraising the source of information, assessing the validity of conclusions, and examining our own underlying assumptions.
Hindsight Bias: This is the tendency to believe, after learning an outcome, that one would have predicted or foreseen it prior to it occurring. This is also commonly referred to as the "I knew it all along" phenomenon.
Peer Reviewers: These are independent scientific experts who read and evaluate research studies before they are published. Their role is to ensure the quality, validity, and scientific integrity of the work.
Theory: An explanation that utilizes an integrated set of principles to organize observations and predict specific behaviors or events.
Hypothesis: A testable prediction that is often implied by a theory, allowing the theory to be put to the test.
Falsifiable: A critical requirement for scientific inquiry meaning that a theory or hypothesis must be able to be disproven by experimental results or direct observation.
Operational Definition: A very carefully worded statement describing the exact procedures and operations used in a specific research study. These are necessary to allow for precise replication.
Replication: The process of repeating the essence of a research study, typically with different participants in different situations. This is done to determine whether the basic findings of the original study can be reproduced and generalized.
Descriptive and Qualitative Research Methods
Case Study: A descriptive technique in which one individual or one specific group is studied in great depth. The goal is often to reveal universal principles that might apply to a broader population.
Naturalistic Observation: This involves observing and recording behavior in naturally occurring situations. The researcher does not try to manipulate or control the environment or the subjects.
Survey: A descriptive technique used to obtain the self-reported attitudes or behaviors of a particular group. This is typically achieved by questioning a representative, random sample of that group.
Social Desirability Bias: The tendency for respondents to answer questions in a way they believe will be viewed favorably by others, rather than answering truthfully.
Self-Report Bias: Any tendency for participants to inaccurately report their own behaviors, beliefs, or experiences, whether intentionally or unintentionally.
Sampling Bias: A flawed process in the selection of participants that produces an unrepresentative sample of the population.
Population: All members within a group being studied. Samples are drawn from this entire group.
Random Sample: A sample that fairly represents a population because every member of that population has an equal chance of being included in the study.
Correlation and Measurement
Correlation: A measure of the extent to which two factors vary together. It indicates how well either factor can predict the presence or change in the other.
Correlation Coefficient: A statistical index that represents the relationship between two things. This index ranges from to .
Variable: Anything in a study that has the capacity to change or vary.
Scatterplot: A graph consisting of a cluster of dots, where each dot represents the values of two variables. The slope of the dots suggests the direction of the relationship (positive or negative), while the amount of scatter indicates the strength of the correlation (less scatter indicates a stronger relationship).
Illusory Correlation: Perceiving a relationship between variables where none actually exists, or perceiving a relationship as being stronger than it is in reality.
Regression Toward the Mean: The statistical tendency for extreme scores or extreme events to fall back, or regress, toward the average over time.
Experimental Research and Design
Experiment: A research method where an investigator manipulates one or more independent variables to observe the effect on a behavior or mental process (the dependent variable). This method uses random assignment to control other relevant factors.
Experimental Group: The specific group in an experiment that is exposed to the treatment, which is one version of the independent variable.
Control Group: The group in an experiment that is not exposed to the treatment. This group serves as a baseline comparison for evaluating the actual effect of the treatment.
Random Assignment: The process of assigning participants to experimental and control groups by chance. This is done to minimize preexisting differences between the groups before the experiment begins.
Single-Blind Procedure: A procedure where the participants are kept uninformed (blind) about whether they are receiving the actual treatment or a placebo.
Double-Blind Procedure: An experimental procedure where both the research participants and the research staff are ignorant (blind) as to whether the participants have received the treatment or a placebo. This is commonly used in drug-evaluation studies.
Placebo Effect: Experimental results that are caused by expectations alone. This refers to any effect on behavior caused by the administration of an inert substance or condition that the recipient assumes is an active agent.
Independent Variable: The factor in an experiment that is being manipulated by the researcher. This is the variable whose effect is the subject of the study.
Dependent Variable: The outcome that is measured in an experiment. It is the variable that may change in response to manipulations of the independent variable.
Confounding Variable: A factor other than the independent variable that might produce an effect in the experiment, potentially tainting the results.
Experimenter Bias: A process where the researchers performing the study influence the results, either consciously or unconsciously, to portray a specific or desired outcome.
Validity: The extent to which a specific test or experiment actually measures or predicts what it is intended to measure or predict.
Quantitative Research: Research that focuses primarily on gathering numerical data and generalizing those results across groups of people.
Qualitative Research: Research that focuses on understanding underlying reasons, opinions, and motivations. This is achieved through non-numerical data collection.
Ethics in Research
Informed Consent: The ethical requirement of providing potential participants with enough information about a study to enable them to make an educated choice about whether they wish to participate.
Debriefing: The post-experimental explanation provided to participants. This includes explaining the purpose of the study and any deceptions that may have been used during the process.
Statistical Analysis and Data Interpretation
Descriptive Statistics: Numerical data used to measure and describe the characteristics of groups. This includes measures of central tendency and measures of variation.
Histogram: A bar graph used to depict a frequency distribution.
Mode: The score that occurs most frequently within a given distribution.
Mean: The arithmetic average of a distribution. It is calculated by adding all the scores together and then dividing by the total number of scores.
Median: The middle score in a distribution; half of the scores fall above this number and half fall below it.
Percentile Rank: The percentage of scores in a distribution that a specific score falls above or equals.
Skewed Distribution: A representation of scores that lacks symmetry around their average value, indicating that the data is weighted toward one end of the scale.
Range: The difference between the highest score and the lowest score in a given distribution.
Standard Deviation: A computed measure that signifies how much scores vary around the mean score.
Normal Curve: A symmetrical, bell-shaped curve describing the distribution of many types of data. Most scores fall near the mean, with approximately falling within one standard deviation of the mean. Fewer scores occur near the extremes.
Inferential Statistics: Numerical data that allows researchers to generalize and infer from sample data the probability of something being true of the larger population.
Meta-Analysis: A statistical procedure for combining the results of many different research studies to identify overall trends or findings.
Statistical Significance: A statistical statement indicating how likely it is that an obtained result occurred by chance.
Effect Size: A measure reflecting the strength of the relationship between two variables or the specific magnitude of an experimental effect.