Wow. That's a quite telling chart (and it's insane to me to think that 5% of total print articles would cover immigration).
1. Why just the Daily Mail? Is that the only paper that matters in Britain, or just the one that happens to correlate?
2. I would expect public opinion to lag coverage in the paper if there were a causal relationship. This graph is over too great a period to really see that, but if the creator wants to convince me, they'd show that.
3. I might expect the lag to differ when coverage is increasing vs. decreasing. Again, if I'm to believe this graph, more context would help.
4. No consideration of other factors that might lead to changes in public concern?
5. No consideration of factors that might lead to *both* an increase in coverage *and* an increase in concern?
You believe this. (I also tend to believe it.) But why do we believe it? Are we basing that belief on data? Or on conjecture?
This chart is the first one I've seen that starkly lays out an argument based on data that this effect exists.