In the complex world of policy research, US think tanks hold an influential position. These intellectual powerhouses are instrumental in shaping policy through their rigorous research, advisory roles and active engagement with policymakers. Choosing the right think tank for your research, however, requires careful analysis. Your decision can greatly impact the quality of your research, the reach of your policy recommendations, and potentially, the direction of national or international decisions. To guide your selection process, consider posing several critical questions to your prospective think tanks.

The first question pertains to the scope and nature of the think tank's research. What are the primary areas of focus? Are they broadly based or specialized? An understanding of the think tank's main research domains can elucidate whether their expertise aligns with your research requirements. A think tank specializing in economic policies, for instance, may be ill-equipped to advise on environmental issues. The research scope can also provide insight into the think tank's potential biases, an aspect to consider for maintaining objectivity in your policy research.

Similarly, explore the methodologies employed by the think tank. Are they predominantly quantitative or qualitative? Do they lean on case studies or statistical models? The research techniques utilized can significantly influence the direction and conclusions of your policy research. For example, a think tank that relies heavily on quantitative methods may provide a more empirical, data-driven perspective, while those favoring qualitative methods might offer richer contextual insights.

In the same vein, delve into the think tank's data sourcing and handling practices. Where do they acquire their data? How do they ensure its reliability and validity? In an era marked by the proliferation of big data and increasing concerns of data privacy, these questions hold substantial weight. A think tank that relies on unverifiable or ethically dubious data sources could undermine the credibility of your policy research.

Next, probe into the think tank's network and influence. Who are the key stakeholders they interact with? How often do they engage with policymakers? The extent and nature of a think tank's connections can significantly impact the reach and impact of your policy recommendations. A think tank with a robust network in the policy realm may be better positioned to present your research to key decision-makers.

Further, the temporal factor is critical. When was the think tank established? When did they last alter their research focus or methodologies? The historical trajectory of a think tank can shed light on its adaptability and relevance in the dynamic policy landscape.

The funding sources of think tanks are equally important to examine. How is the think tank financed? Are the funders publicly disclosed? The financial backing of a think tank can influence its research orientation and independence. Think tanks primarily funded by government grants, for instance, may be more inclined towards state-centric research, while those supported by private donations might lean towards market-centric policies.

Lastly, one cannot overlook the human factor. Who forms the think tank's research team? What are their qualifications and experience? The quality of your policy research is invariably linked to the expertise and proficiency of the think tank's researchers.

To conclude, the choice of a think tank for policy research is a critical decision intertwined with numerous factors. It necessitates a thorough understanding of the think tank's research focus, methodologies, data practices, network, historical trajectory, funding sources, and research team. By posing these questions, you can critically evaluate potential think tanks and select the one most aligned with your research objectives. Not just an academic exercise, the selection of a think tank has far-reaching implications for the formulation of informed, effective policies that can shape societal trajectories at the national and international levels.