Types of Clinical Trial

 Types of Clinical Trial:

• Randomized
• Non-Randomized 
• Crossover
• Factorial

Randomized Control Trial (RCT):

    Randomized control trials (RCTs) are studies in which participants are randomly assigned to an experimental group or a control group. The experimental group receives the intervention that is being studied and control group receives the placebo (or a standard treatment). As RCTs are mostly double blinded neither Principal Investigator nor Patients know the assignment of groups. After tests are completed the results of experimental group and control groups are analyzed and compared.

Non-Randomized Control Trial:

    

    In non-randomized controlled trials, participants are allocated into experimental and control groups by the principal investigator. It is appropriate to use a non-randomized controlled trial design when the act of random allocation may reduce the effectiveness of the intervention. Non-randomized controlled trials have the potential to study two groups that are not strictly comparable. 

Crossover Randomized Control Trial:

    In a crossover trial, participants are randomly allocated to study group where each group consists of a sequence of two or more treatments given consecutively. The simplest model is the AB/BA study. Subjects allocated to the AB study group receive treatment A first, followed by treatment B, and vice versa in the BA group. Crossover trials allow the response of a participant to treatment A to be contrasted with the same participant’s response to treatment B. Removing participant's variation in this way makes crossover trials potentially more efficient than similar sized, parallel group trials in which each subject is exposed to only one treatment.

Factorial Randomized Control Trial:

    

    Factorial trial address two (or more) intervention comparisons carried out simultaneously, using four (or more) intervention groups. Most factorial trials have two ‘factors’, each of which has two levels (i.e., two possible groups of allocation); these are called 2 × 2 factorial trials. 

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