What do you mean that consciousness cannot be measured? We can perceive it and talk about it, can't we? Chamlers says that the reason we talk about having qualia has nothing to do, causally, with our experience of qualia but I think we can dismiss that idea out of hand. So by asking people questions about their experiences and getting large enough sample sizes we have a means to conduct a quantitative and scientific investigation of consciousness.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3971003/