Doesn&#x27;t independence mean that, for two events, the occurrence of one event doesn&#x27;t effect the probability of the other event? You can observe correlations between two independent events, they just can&#x27;t be causally connected.<p>In your example, the press conference where Trump drinks kitty blood is driving the change in probability for all primaries, so it&#x27;s functioning as a confounding variable.<p>You wouldn&#x27;t expect the results of one primary to affect the results of another (because they&#x27;re happening near simultaneously), so I think it&#x27;s safe to assume independence.