So why does Yougov on this site have Trump ahead by 2.4% on August 1st, but on RCP, Yougov has Hillary ahead by 3% on August 2nd?
And why does Ipsos/Reuters on this site have Trump up by 3.8% on August 4th, but on RCP it has Hillary up by 4% on the same day?
Then CNN on this site has Hillary up by 1.9% on July 31st, but on RCP has her up by 9% on August 1st.
I stopped after this. It’s completely off. I’ll stick with RCP.
Using CNN, your last example, if you look at the lower data on this site, you’ll see that they have CNN bias recorded at 7.1%.
That would be claiming that CNN had decreased their Hillary bias and then increased it again.
It would seem to be, in my opinion, looking at the chart, an attempt to show a Trump convention bounce and then to take it away again.