The January 15 post  on group testing generated a nice collection of comments, more interesting alternatives, and requests for references.
What I was looking for in the literature to use as a reference I didn’t find—a definitive why-to/how-to article on group testing that laid out the educational rationale for using the approach (justified with research) and followed with an overview of the various options. If you know of such a resource, please direct us to it. Otherwise, someone, please write it.
Most of the options I highlighted in that post have been used by more than one teacher and in more than one study. As a result, the references below serve as examples of different collaborative testing approaches that deserve our consideration. The majority of the articles are not in open access publications, but I suspect copies can be obtained through interlibrary loan programs if your institution doesn’t have its own subscription.
Pandey, C., and Kapitanoff, S. “The Influence of Anxiety and Quality of Interaction on Collaborative Test Performance.” Active Learning in Higher Education, 2011, 12 (3), 163-174.
In this study, students come to class prepared for each of the six quizzes used in the course because they don’t know before class if they will be taking the quiz individually or with a partner.
Abstract: http://alh.sagepub.com/content/12/3/163.abstract 
Hoke, M. M., and Robbins, L. K. “The Impact of Active Learning on Nursing Students’ Clinical Successes.” Journal of Holistic Nursing, 2005, 23 (3), 348-355.
Students first do the quiz individually and then have a period of time during which they can collaborate on those test questions they can’t answer or aren’t sure they’ve answered correctly. After this collaboration, students may change answers on their quiz, which is graded individually.
Abstract: http://jhn.sagepub.com/content/23/3/348.abstract 
Kapitanoff, S. H. “Collaborative Testing: Cognitive and Interpersonal Processes Related to Enhanced Test Performance.” Active Learning in Higher Education, 2009, 10 (1), 56-70.
In this study, each student completed a 50-question multiple-choice test and a 15-question short-answer test. That was followed by a period during which students collaborated on 20 of the exam questions selected by the teacher, they then submitted their answers as a group.
Abstract: http://alh.sagepub.com/content/10/1/56.abstract 
Sroug, M. C., Miller, H. B., Witherow, D. S., and Carson, S. “Assessment of a Novel Group-Centered Testing Scheme in an Upper-Level Undergraduate Molecular Biotechnology Course. Biochemistry and Molecular Biology Education, 2013, 41 (4), 232-241.
In this model, the collaboration occurred first. In groups, students prepared a written response to a take-home essay question. Immediately after submitting their collective responses, students took a multiple choice exam individually. Content covered in both exams was the same, but the questions were different.
Abstract: http://onlinelibrary.wiley.com/doi/10.1002/bmb.20701/abstract 
Clinton, B. D., and Kohlmeyer III, J. M. “The Effects of Group Quizzes on Performance and Motivation to Learn.” Journal of Accounting Education, 2005, 23 (2), 96-116.
Here individual quiz grades were averaged with the group quiz score. The approach was used to encourage a serious discussion of the quiz questions during the group interaction.
Abstract: http://www.sciencedirect.com/science/article/pii/S0748575105000321 
Rao, S. P., Collins, H. L., and DiCarlo, S. E. “Collaborative Testing Enhances Student Learning.” Advances in Physiology Education, 2002, 26 (1), 37-41.
Individual quiz scores and the group score were combined here as well, but using a weighted formula with 80% of the grade determined by the individual quiz score and 20% by the group score.
Full text: http://advan.physiology.org/content/26/1/37.full 
Slusser, S. R., and Erickson, R. J. “Group Quizzes: An Extension of the Collaborative Learning Process.” Teaching Sociology, 2006, 34 (July), 249-262.
In some group testing models, group grades are used, and here’s one such example. In this case, students first took a reading quiz individually, they then collaborated in a group, after which individual answers could be adjusted. One randomly selected quiz from each group was selected and graded, with that score recorded for each group member.
Abstract: http://tso.sagepub.com/content/34/3/249.abstract 
Russo, A., and Warren, S. H. “Collaborative Test Taking.” College Teaching, 1999, 47 (1), 18-20.
In this English course, students got to choose whether they collaborated with others on the test in this very open, whole class collaboration model. Although some faculty worry that collaboration will inflate exam scores, that didn’t occur in these courses. However, research evidence is somewhat mixed on this point and most of it documents a modest increase in scores.
Abstract: http://www.tandfonline.com/doi/abs/10.1080/87567559909596072#preview