One way to analyze Ira Levin's crime novel is through the lens of class. You might discuss the ways in which economic status and money impact Bud's trajectory.

Early on, the narrator makes it clear that Bud is not rich. His dad worked at textile mills. Sometimes his mom had to work as a seamstress if extra money was needed. You might analyze how Bud's reduced circumstances motivate him to attain success. You might discuss the things—the murders, to be specific—that Bud does in order to stay on that path to success. You could analyze the ways in which money, success, and murder seem inextricably linked. Alas, if Bud came from wealth, there might not have been such pressure on his relationships with the Kingship daughters. Perhaps Dorothy and Ellen would still be alive.

Speaking of Dorothy and Ellen, you could analyze the novel through a gender angle. You could discuss the sexist ways in which the novel presents women. You might wonder why Dorothy is punished for the pregnancy and not Bud. You might also focus on the ways Bud seems to treat all of the daughters as objects instead of as humans. For Bud, it's like they're a means to an end.

Lastly, you could analyze the novel by discussing Bud in a general sense. You might think about why Levin opted to center his novel on such a ruthless character. You might discuss how Bud's villainy keeps the reader interested. You might speculate on whether it would be possible to publish a novel like this right now in 2020.