Understanding Clinical Trial Design - Research Advocacy Network

UNDERSTANDING CLINICAL TRIAL DESIGN: A TUTORIAL FOR RESEARCH ADVOCATES
Bias Bias in a sample is the presence or influence of any
factor that causes the population or process being
sampled to appear different from what it actually is. Bias
is introduced into a sample when data are collected
without regard to key factors.
Biomarker A characteristic (e.g., protein, gene) that is objectively
measured and evaluated from a biological sample (e.g.,
tissue, blood) as an indicator of normal biological
processes, pathogenic processes, or pharmacologic
responses to a therapeutic intervention.
Blinding A procedure in which one or more parties to the trial are
kept unaware of the treatment assignment. Double (or
triple) blinding means that investigators and/or health
care providers, in addition to patients, are unaware of
the treatment assignments.
Clinical Endpoint An occurrence that measures the study hypothesis. It is
often a characteristic or variable that reflects how a
patient feels, functions, or survives, and used to measure
whether a treatment is effective.
• Primary—what a trial is designed to assess
• Secondary—other endpoints of interest
Clinical Trial A type of research study that assesses medical questions
in people. These studies often test new methods of
screening, prevention, diagnosis, or treatment of a
disease.
Comparison Group; The treatment received by the comparison or control
Control Intervention group, often a placebo. In cancer trials, the control
or Control Treatment intervention is usually the current standard of care.
Confounding In research design, the problem that arises when two or
more causal variables , often an independent variable and
an extraneous variable, are not properly controlled, so
that their separate effects on the outcome measure can
not be disentangled.
Comparison or A group of patients who are not treated with the experi-
Control Group mental intervention (e.g., no therapy, a different therapy,
or Arm or a placebo) This group is compared to the group that
receives the experimental intervention, to see if the
experimental intervention is effective.
Correlation A statistical technique for determining the extent to
which variations in the values of one variable are
associated with variations in the value of another.
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