Psych/Soc Experimental Design

Independent Variable

Controlled by researcher.

Dependent Variable

Measured by researcher.

Quasi-experimental

Lack random assignment that is needed for a true “experiment”

Mixed-methods

Contains the use of both quantitative and qualitative data collection methods.

Case-control Studies

Observational studies that aim to compare two groups: a “case group” that exhibits the condition the researchers aim to understand and a “control group” that does not exhibit the condition.

Confounding Variables

Other variables that can impact the results of a study.

Cross-sectional study

Observational research that analyzes data collected at a single point in time.

Surveys often used to provide data.

Longitudinal Study

Data collected repeatedly over time.

Cohort Study

Longitudinal observational study that aims to find a potential cause to a condition of interest.

Experimental Study

Aims to understand the cause-and-effect relationship between certain independent variables and dependent variables.

Ethnographic Study

Aims to understand people in their environments (emphasizing understanding of that group’s culture and practices).

Internal Validity

A study’s ability to establish a cause-and-effect relationship between two factors.

For a high internal validity, we should not be able to attribute the value of the dependent variable to anything other than the independent variable.

External Validity

The extent to which researchers can generalize the findings of a study to other situations or the general population.

Construct Validity

How well a test is able to measure the concept it was designed to evaluate.

Predictive Validity

The ability of a test to predict a future outcome. Can be better understood through correlations.

The stronger the correlation between the test and the outcome of interest, the higher the degree of predictive validity.

Placebo

An inactive substance or intervention that is indistinguishable from the active drug or treatment being tested. Designed to have no therapeutic value to give insight into if the drug of interest is truly the cause of the observed effect.

Control

Element that is unaffected by other variables in the study.

Negative Control

Not expected to cause changes in the dependent variable.

Positive Control

Some other treatment that is expected to produce an effect that is similar to that of the independent variable.

Bias

Occurs when error introduced to the study results in a higher prevalence of one outcome over another.

Selection Bias

There is allocation of participants to different treatment groups in a way such that proper randomization is not achieved.

Experimenter Bias

Errors in the methods or data interpretation that can be attributed to the researcher’s behavior or beliefs.

Implicit Bias

Occurs unintentionally and affects an individual’s judgement and behavior.

Social Desirability Bias

Prevalent when participants provide answers that align with societal expectations rather than their personal beliefs. (Colin Bridgerton lmao)

Observational Studies

Involve observing participants in their most natural settings. Data is collected solely through observation. Researchers do not interfere with participants or their environments.

Experimental Studies

Researchers assign participants to treatment and control groups. Interfere with the participants.

Longitudinal Observational Studies

Follows a group of participants over an extended period to observe and analyze changes in the variables of interest. Allows researchers to study the same individuals or groups repeatedly, collecting data multiple times to assess trends, patterns, and associations over time.

Retrospective Observational Study

Involves analyzing data or records from the past to study the relationship between variables over a period of time. Allows researchers to explore how factors may have influenced outcomes in the past.

Correlation

Measurement that describes the extent to which two variables are related.

1. Positive - Variables move in the same direction

2. Negative - Variables move in opposite directions

3. No correlation - no effect between variables

Repeatability

The ability to collect similar results upon data recollection.

Practical Significance

The findings of research being practical to implement into everyday life.

Considered such when the consequences of the independent variable are significant enough to be meaningful in real life.