What is the standard of proof used by the courts in revocation proceedings?

"As the language of section 1203.2 would suggest, the determination whether to grant or revoke probation is largely discretionary. [Citations.] The correct standard of proof to be used by the trial court in assessing whether there exists `reason to believe' the probationer has violated his probation or committed a new offense has been variously stated [citations]. Yet the authorities are unanimous in concluding that the standard of proof used in a criminal trial, namely the `beyond a reasonable doubt' standard [citation] is inapplicable to the probation revocation hearing. [Citations.] Accordingly, probation may be revoked despite the fact that the evidence of the probationer's guilt may be insufficient to convict him of the new offense. [Citations.]" (In re Coughlin (1976) 16 Cal.3d 52, 56.) "The standard of proof in probation revocation proceedings is proof by a preponderance of the evidence. [Citation.]" (People v. Stanphill (2009) 170 Cal.App.4th 61, 72.)