I received an email from HR that we have your CV and we want to proceed with it. A few days later a senior scientist emailed me and set up a time for a phone call. She also mentioned what we are going to talk about in the email. The whole process (from them receiving the referral letter and CV to the phone call took around one week).
The first interview went very well. The interviewer was very friendly and made very comfortable during the interview. She was trying to learn about my research and expertise with a few follow up questions. She also talked about Exponent and introduced the company. The call took around 40 min and she said the interview went well.
A few days later, I received an email form another senior scientist from another office. we set up a time for a skype call but the interviewer emailed me 15 min before the interview saying he cannot do it and postponed it for a week! The second time I was prepared for the Skype call but he just called me!!! He did not sound friendly, nor interested in the interview. At first he asked me a few questions about my research but proceeded with asking technical questions related to his own background which was fracture and mechanical properties of metals (no where in my CV nor my cover letter I claimed any experience in fracture of metals!!!). It felt like a test rather than an interview,and I started to loose confidence. Unlike the first one, I did not enjoy the second interview at all, and did not do a good job. A week later I received an email form HR that they will proceed with the other applicants.
It really depends on your luck that who will interview you. While the first one was friendly and tried to learn about me, the second interviewer was trying to test me on the stuff that he knows.