How do you track consumer preferences for sustainable packaging?

We've had good results combining conjoint analysis with shelf simulation tests — lets you isolate how much sustainable packaging actually drives purchase versus just getting lip service in surveys. Qualtrics or Sawtooth work well for the conjoint piece. One thing we consistently find: willingness-to-pay for eco packaging varies a lot by category, so make sure you're testing within your client's specific vertical, not relying on general benchmarks.