Anyone researched how defence contractors pick new suppliers?

For defence procurement research, I'd start with a mix of expert interviews (former procurement officers are gold) and reviewing publicly available RFP documents to map out the actual decision criteria. FPDS.gov is a solid free resource if you're in the US — you can reverse-engineer supplier selection patterns from contract award data. Then layer in a quantitative survey with current procurement decision-makers using a conjoint or trade-off exercise to weight the key factors like compliance history, pricing, and past performance.