Related Experiment Video
Updated: Aug 18, 2026

Applying an eMASS Customization Program as a Research Tool to Evaluate Consumer Benefits
Published on: September 27, 2019
Impact of referral source and study applicants' preference for randomly assigned service on research enrollment,
Cathaleene Macias1, Paul Barreira, William Hargreaves
1Community Intervention Research, McLean Hospital, 115 Mill St., Belmont, MA 02478, USA. cmacias@mclean.harvard.edu
Objective:
The inability to blind research participants to their experimental conditions is the Achilles' heel of mental health services research. When one experimental condition receives more disappointed participants, or more satisfied participants, research findings can be biased in spite of random assignment. The authors explored the potential for research participants' preference for one experimental program over another to compromise the generalizability and validity of randomized controlled service evaluations as well as cross-study comparisons.
Method:
Three Cox regression analyses measured the impact of applicants' service assignment preference on research project enrollment, engagement in assigned services, and a service-related outcome, competitive employment.
Results:
A stated service preference, referral by an agency with a low level of continuity in outpatient care, and willingness to switch from current services were significant positive predictors of research enrollment. Match to service assignment preference was a significant positive predictor of service engagement, and mismatch to assignment preference was a significant negative predictor of both service engagement and employment outcome.
Conclusions:
Referral source type and service assignment preference should be routinely measured and statistically controlled for in all studies of mental health service effectiveness to provide a sound empirical base for evidence-based practice.
Related Concept Videos
Randomized Experiments
Simple randomization
Simple...
Surveys
Blind Procedures
Group Design
Bias
In statistics, a sampling bias is created when a sample is collected from a population, and some members of the population are not as likely to be chosen as others (remember, each member...
Blinding