Understanding Clinical Trial Design - Research Advocacy Network

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UNDERSTANDING CLINICAL TRIAL DESIGN: A TUTORIAL FOR RESEARCH ADVOCATES
Independent Variable Variable that is manipulated, sometimes experimentally,
in order to observe its effects on a dependent variable.
For example, in an investigation of the affect of drugs on
cancer, the independent variable (e.g., drug type or dose)
is manipulated and the affect of this manipulation can
be seen in the change in the dependent variable or
outcome (e.g., survival). A variable that is acted on or
influenced by another variable.
Inductive Methods A form of reasoning, also called empirical induction, in
which a general law or principle is inferred from
particular instances that have been observed.
Inference A conclusion reached on the basis of evidence and
reasoning.
Informed Consent A process in which a person is given important facts
about a medical procedure or treatment, a clinical trial,
or genetic testing before deciding whether or not to
participate. It also includes informing the patient when
there is new information that may affect his or her
decision to continue. Informed consent includes
information about the possible risks, benefits, and limits
of the procedure, treatment, trial, or genetic testing.
Institutional Review An IRB is a committee with federal regulatory authority
Board (IRB) to review and approve research involving human
subjects. An IRB is composed of a diverse group of men
and women with expertise in science, ethics, and other
non-scientific areas.
Intent-to-Treat In reality, not all patients who enroll in a clinical trial
complete the trial as planned. They may drop out, die,
switch treatments, etc. How to deal with the data of
such patients is problematic because the patients who
drop out are often different from those who complete
the trial. Thus, biostatisticians often conduct two
analyses—one including all patients assigned to
treatment arms (i.e., those intended-to-be-treated) and a
second including only patients who actually were treated.
When the results of these two analyses differ, it is likely
that the intervention influenced the propensity of
patients to drop out of the trial.
Interaction The situation in which a treatment difference (e.g.,
difference between experimental and control) is
dependent on another factor (e.g., study site, organ site,
gender).