I on the other hand think that what the president says and tweets can and does have an effect on people.
Absolutely it does. He has the biggest megaphone.
There is no bigger megaphone then the one wielded by a president. And, in Trump's case, that megaphone has been in the form of tweets, more then any president before him. I remember suggesting, that if he were elected, he would govern mostly via Twitter and rallies. Hasn't quite turned out that way, executive orders have been prevalent, but Twitter and rallies have seen to it that the focus of the media has been on Trump, and to a saturated degree. But that suits him fine. (I'd love to see a week go by where the media ignores every tweet, and refuses to cover his rallies. Too bad, he snares them every time).
But do his hateful tweets and divisive rally speeches equate to an increase in hate crimes? I believe a president's words matter. If a president is scapegoating minorities with his words, then the very reach of his words, via social media, via live rallies attended by thousands, and sound bites of those rallies and tweets provided by the media, is huge. Far greater then any private citizen. Filling those tweets and rallies with hate, scapegoating, and "otherizing" Hispanics, at the very least, renders approval to those who feel the same way. It's wrong. Stop it. Don't need a direct link between Trump and El Paso. Just stop it.
But, FWIW, and both these studies must have flaws.
Do Trump tweets spur hate crimes?:
https://www.scientificamerican.com/article/do-trump-tweets-spur-hate-crimes1/
The actual study, PDF file at link:
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3149103
And this study has come up on cable networks in recent days: hate crimes up 226% in counties that held Trump rallies during 2016 campaign:
https://thehill.com/blogs/blog-brie...s-rose-by-226-percent-in-counties-where-trump