Hi simmas,
Did think about fitting a logistic regression model with responded/not responded as an outcome and the characteristics you mention (firmagraphics, behaviours etc) as predictors?
In fact, logistic regression models the probability of event, so in your case it's the model for probability of site responding, and you can rank the sites based on their predicted probabilities. Also you can put the sites into categories according to the predicted probabilities of responding, for example low:<10%, mid:10-30%, high:>30%.
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