I agree that which CRO to be chosen should depend on the size of trials, the resources, manpower required other than that the cost that they will be charging as well as we have to see if the CRO does provide us the quality of results that we require.
It all depends on the management how much funding they are ready to provide. Depending on the funding we decide which CRO should we go forward with if there are many CRO's which meet our specifications.

For many companies, particularly the smaller ones engaged in clinical trials, outsourcing might not be so much a choice, but a necessity. As we know, clinical trials can be often very complex projects and it isn’t often feasible to conduct the whole process in-house, nor does it make sense from a financial perspective. Thus, it is critical to choose the right CRO. From my experience, it is important to choose partners that are not only capable of doing the work, but can work well as a team. The team responsible for evaluating and selecting (or “qualifying”) the CRO should be composed of team members with wide range of expertise and typically they would visit the facility as well as hold meetings with various levels of staff (management, scientist, QA, etc). It is very important to do due diligence and establish a predetermined set of criteria against which the service provider will be judged. The criteria would range from location, areas of capability, regulatory and compliance and the organizational and operational areas to be evaluated. Typically three CROs are evaluated and the best that meets predetermined criteria is selected.

Selecting the right CRO to manage a clinical trial can be a critical decision in the program’s successful outcome. It is important to consider the experience of CRO in that particular area and important to consider the financial stability of CRO. Appropriate CRO infrastructure is essential to support your project requirements, Ask what software they use to track project performance and how their clinical information system is organized. Do they maintain clinical data in such a way that is 21 CFR Part 11 compliant? What steps must be taken to export data maintained at the CRO into your company’s system and is the process secure. How does the CRO manage essential study documentation? Ensure that your CRO has a proven track record of obtaining valuable patients and providing high-quality patient data and determining the actual number of patients that meet the inclusion and exclusion criteria of the study. The other important factors are cost,transparency and responsiveness.

ec52 and Sk90, thank you for your responses. The answers you've provided about CRO selection criteria, questions to ask when inquiring about them, and selecting at least three to evaluate are valuable insights. Sk90, the data exporting point you bring up is becoming more and more important as technology evolves, will the data be stored onsite or will they be using the cloud? the security concerns about these storage options are valid. Cost, transparency and responsiveness play into the idea that a larger CRO may be less responsive to a small trial due to the fact that they aren't bringing in as much revenue as larger trials. ec52, selecting team members with the correct experience and background as the individuals to evaluate the CROs is also another valid point.