Where an expert witness did not indicate how his data led to his conclusion, the U.S. District Court did not err in striking testimony and granting summary judgment to the defendant.The 7th U.S. Circuit Court of Appeals affirmed a decision by U.S. District Judge Joan B. Gottschall.Varlen Corp. owned and operated two industrial facilities related to railroad operations. At the first site, LASI , Varlen performed operations …