BI 2.1.1 Observational and Experimental Study terms

Cross-Sectional Studies

A research study that involves a single observations (such as an interview or questionnaire), which may be useful to determine how variables affect each other at the same time and period.

Experimental Study

A type of study in which all variable measurements and manipulations are under research control. The goal of an experiment is to control the environment in such a way that manipulation of the independent variable yields a direct, corresponding change in the dependent variable.

Prospective Cohort Study

A research study that follows over time groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) and compares them for a particular outcome (such as lung cancer).
Outcomes have not yet occurred as study begins. Not always feasible as they take considerable time, money, and resources to complete; and they require a large number of subjects

Retrospective Cohort Study

A research study that follows over time groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) and compares them for a particular outcome (such as lung cancer). Outcomes have already occurred as the study begins

Observational Studies

A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given).

Cohort Studies

A research study that compares a particular outcome (such as lung cancer) in groups of individuals who are alike in many ways but differ by the variable the researcher is studying

Validity

Researchers design studies that minimize or eliminate systematic errors, or biases, in the data collection process.

Control Groups

One group receives the treatment and another group does not.

Randomization

The control group and treatment group are chosen at random.

Blinding

blinding (when performing studies involving humans) allows researchers to eliminate bias that participants or investigators have introduced by having knowledge of the treatment or control conditions in an experiment.

Single Blind

participant doesn't know whether he or she has been assigned to a treatment or control group.

Double Blind

Neither the participant nor the researcher knows whether the participant has been allocated to a treatment or control group.

Triple Blind

Neither the participant, the researcher, nor the response gatherer knows whether the participant has been allocated to a treatment or control group.

Reliability

A study in which another researcher can perform exactly the same experiment and generate results with the same statistical significance.

Confounding Variables

A variable that was not accounted for in the experimental design, varies systematically with the dependent variable, and prevents a clear interpretation of the effect of the independent variable on the dependent variable.