Blinding | Confounding Variables | Control | Dependent Variable | Experimental Design | Experimental Group | Independent Variable | Intention to Treat | Observational Design | Placebo Effect | Randomization | Reliability | Statistical Significance | Sample | Validity

Blinding

Participants, investigators and/or assessors remain ignorant concerning the treatments that participants are receiving to minimize observer bias. In a single blind study it is may be the participants who are blind to their allocations, or those who are making measurements of interest, the assessors. In a double blind study, both participants and assessors are blind to their allocations. A trial is fully blinded if all the people involved are unaware of the treatment group to which trial participants are allocated until after the interpretation of results.

Confounding Variables

Variables that cannot be controlled and therefore confound or confuse the outcome by leading to erroneous conclusions.

Control

The group that serves as a standard for comparison in experimental studies. It is similar in relevant characteristics to the experimental group but does not receive the experimental intervention.

Dependent Variable

The variable that is observed and measured. The dependent variable is influenced or changed by the independent variable. Synonym: dependent measure.

Experimental Design

Investigators apply an external factor (treatment, intervention, program, etc.) to the experimental group and observe the outcomes.

Experimental Group

The group in an experiment or study that receives the experimental intervention.

Independent Variable

The variable that is manipulated by the researcher. Most experiments consist of observing the effect of the independent variable(s) on the dependent variable(s).

Intention to Treat

A method of analysis in which all patients are analyzed in the group to which they were originally assigned.

Observational Design

Investigators gather data by observing correlations between subjects and variables of interest; investigators do not apply any external factors or intervention.

Placebo Effect

The placebo effect is the inclination of patients to report improvement or side effects not attributable to the intervention.

Randomization

Randomization is a method analogous to tossing a coin to assign patients to treatment groups. It may be performed by using a computer to generate a list of random numbers, which can then be used to generate a treatment allocation list. Also called random allocation.

Reliability

The extent to which the results of an experiment can be reproduced.

Sample

A group of participants selected from a defined population.

Statistical Significance

A conclusion that an intervention has a true effect, based upon observed differences in outcomes between the treatment and control groups that are sufficiently large so that these differences are unlikely to have occurred due to chance, as determined by a statistical test.

Validity

The extent to which a study or experiment measures what it intends to measure.