Ryan gave Romney a small bump in Wisconsin once he picked him, which ended up dissipating and had no effect whatsoever on the final margin. But I don't think Edwards even gave Kerry a temporary bump. Of VP nominees from the last 4 elections, ironically, Sarah Palin probably gave the biggest home state boost.
Palin and Biden, and possibly Cheney. Palin and Biden clearly helped their respective tickets overperform in Alaska and Delaware, respectively, in 2008. The home state boost tends to be most significant in small states.
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