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

By definition, "substantial evidence" requires evidence and not mere speculation. In any given case, one "may speculate about any number of scenarios that may have occurred . . . . A reasonable inference, however, may not be based on suspicion alone, or on imagination, speculation, supposition, surmise, conjecture, or guess work. . . . A finding of fact must be an inference drawn from evidence rather than . . . a mere speculation as to probabilities without evidence." People v. Morris (1988) 46 Cal.3d 1, 21, italics in original, paragraph sign and internal quotation marks omitted.)