What is probable cause for arrest?

As stated in People v. Fischer, 49 Cal.2d 442, 446, 317 P.2d 967, 970: 'Probable cause for an arrest is shown if a man or ordinary caution or prudence would be led to believe and conscientiously entertain a strong suspicion of the guilt of the accused. * * * Probable cause may exist even though there may be some room for doubt. * * * The test in such case is not whether the evidence upon which the officer made the arrest is sufficient to convict but only whether the prisoner should stand trial.'