A party offering an expert witness is entitled to examine him 'as to his qualifications and experience so that the full weight to be accorded his testimony will become apparent.' (Moore v. Belt (1949) 34 Cal.2d 525, 532 [212 P.2d 509]; Salmon v. Rathjens (1907) 152 Cal. 290, 299 [92 P. 733].) Such examination 'should not be limited by narrow and stringent rules.' (Eble v. Peluso (1947) 80 Cal.App.2d 154, 156-157 [181 P.2d 680].) The purpose of permitting a party producing an expert to question him as to his educational background, training, and experience in his area of expertise is not only to establish 'the competency of the witness to the satisfaction of the court, but also for the purpose of making plain the strength of the witness's [sic] grounds of knowledge and the reason for trusting his belief.' (Salmon v. Rathjens, supra, 152 Cal. 290, 299; 2 Wigmore, Evidence (Chadbourne rev. 1979) §§ 562, subd. (2), 655, pp. 759-760, 884-886.)