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Understanding Clinical Trial Design - Research Advocacy Network

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UNDERSTANDING CLINICAL TRIAL DESIGN: A TUTORIAL FOR RESEARCH ADVOCATES<br />

Experimental <strong>Design</strong> The general plan of an experiment , including the<br />

method of assigning research participants or patients to<br />

treatment conditions , controlling extraneous variables ,<br />

manipulating the independent variable , and measuring<br />

the dependent variable or outcome.<br />

Experimental or In clinical trials, a group of patients who receive the<br />

Investigational experimental or investigational intervention.<br />

Group or Arm<br />

Experimental or Term often used to denote a therapy (drug, drug dose or<br />

Investigational combination, device, or procedure) that is unproven or<br />

Intervention not yet scientifically validated with respect to safety and<br />

efficacy in humans.<br />

Frequentist or<br />

Traditional Statistics Traditional approach to statistical inference. Using<br />

hypothesis testing, it allows researchers to draw inferences<br />

about how likely they are to observe their data (or more<br />

extreme data) if the null hypothesis were true. Limits the<br />

relative frequency of drawing erroneous conclusions. It<br />

does not, however, allow researchers to assess the relative<br />

likelihood of competing hypotheses (other than the null<br />

hypothesis) in light of their data.<br />

Historical Controls Control group based on previous trials. Using historical<br />

controls is less costly in terms of time and money than<br />

including a randomized control group in a new trial.<br />

However, it typically introduces many unknown biases<br />

and is not generally acceptable for phase III trials.<br />

Hypothesis A tentative proposal made to explain certain observations<br />

or facts that require further investigation to be verified.<br />

Hypothesis Testing Hypothesis testing refers to the process of using<br />

statistical analysis to determine if the observed<br />

differences between two or more samples are due to<br />

random chance (as stated in the null hypothesis) or to<br />

true differences. A null hypothesis (H0) is a stated<br />

assumption that there is no difference in outcomes for<br />

two or more populations. The alternate hypothesis is a<br />

statement that the observed difference or relationship<br />

between two populations is real and not the result of<br />

chance or an error in sampling. Hypothesis testing is the<br />

process of using a variety of statistical tools to analyze<br />

data and, ultimately, to reject or not reject the null<br />

hypothesis.<br />

Incidence The frequency of occurrence or onset of new cases of a<br />

disorder as a proportion of a population in a specific<br />

time period, usually expressed as the number of new<br />

cases per 100,000 per annum.<br />

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