I have no idea how a researcher is supposed to show that CP induces demand in pedophiles without running into some pretty massive fundamental issues. There are already troubles getting people to admit who they're going to vote for anonymously, so getting people to admit that they are using child pornography anonymously seems like an extremely tall task.

I've also seen studies trying to show the opposite, or trying to show that there is no causation either way, so I don't think there is anything resembling a consensus on this issue at all.