The ranges are quite wide. Even within a given company, the range would be pretty broad for each pay grade, e.g., a research associate’s I salary could range from $45k to $60k. That is quite a gap. Long-term employees who started when companies were small also experience the so-called salary compression - it is a term of the art.
http://www.shrm.org/hrdisciplines/compensation/articles/pages/salary-compression-lid.aspx