Editing Parallel study

{{Short description|Research model}}
A '''parallel study''' is a type of [[clinical study]] where two groups of [[medical treatment|treatments]], A and B, are given so that one group receives only A while another group receives only B. Other names for this type of study include "between patient" and "non-crossover". This is unlike a [[crossover study]] where at first one group receives treatment A and later followed by treatment B while the other group receives treatment B followed by treatment A. There are, however, certain characteristics that allow for differentiation between these two types of trials. For example, a parallel study would be more appropriate if any concerns about [[carryover effect]]s were present. This type of study might also be more beneficial if the disease or disorder being studied has a likely chance of progression during the time in which the study takes place.  One significant issue with parallel studies, though, is the concept of [[intra subject variability]], which is defined as variability in response occurring within the same patient.<ref name=Max>{{cite book|last=Max|first=Mitchell B.|title=Symptom Research: Methods and Opportunities|author2=Joanne Lynn|publisher=National Institute of Dental and Craniofacial ResearchNational Institutes of Health}}</ref>

The two treatment groups in a parallel study can either consist of two completely separate treatments (i.e. different drugs), or simply different doses of a common drug. One major aspect of a parallel study is [[randomization]] – this ensures that the results are accurate and have a lower risk of being biased. Control groups utilizing a [[placebo]], or active control, are often used in this type of study.<ref name=Foulkes>{{citation|last=Foulkes|first=Mary|title=Study Designs, Objectives, and Hypotheses|year=2008|publisher=Johns Hopkins Bloomberg School of Public Health}}</ref>

==References==
{{reflist}}
* http://hedwig.mgh.harvard.edu/sample_size/size.html

{{DEFAULTSORT:Parallel Study}}
[[Category:Clinical trials]]
[[Category:Research methods]]