Deduction is a top down approach that takes premises and then a conclusion, while induction is a bottom up approach that forms conclusions from the start of our premises, probability statement.
Hempel identifies two explanatory facts in order to provide a valid explanation: particular facts that describe the real situation, contingent facts, and uniformities expressible in terms of general laws.
Hempel argues that the warming of the cool air trapped under the hot tumblers would constitute a mere accidental antecedent rather than an explanatory factor for the growth of the bubbles, if were not for the gas laws, which connected the two events.
In a probabilistic explanation, the explanandum is not the logical consequence of the explanans but rather, the explanans makes the explanandum highly likely to occur.
In an inductive statistical model of explanation, the explanandum is not the logical consequence of the explanans but rather, the explanans makes the explanandum highly likely to occur.
In a probabilistic explanation, there is not a lawful connection between the premises and the conclusion, but if the premises are true, the conclusion will occur with more or less probability.