What is the test for substantial evidence in a civil case?

facts. This ultimate determination... presents a "mixed question of law and fact"....' (Jbid., fn. omitted.) Accordingly, we apply a deferential substantial evidence standard [citation] to the trial court's conclusions regarding '"basic, primary, or historical facts: facts 'in the sense of recital of external events and the credibility of their narrators... [Citation.] Having determined the propriety of the court's findings under that standard, we independently decide whether 'a reasonable person [would] have felt he or she was not at liberty to terminate the interrogation and leave.' [Citation.]" (People v. Ochoa (1998) 19 Cal.4th 353, 401-402.)