 Experian LSE:EXPN PLC reported a 41 decline in earnings in the first half and said it expects economic conditions to be tougher over the rest of its financial year, but kept its revenue target unchanged. The credit checking giant reported revenue up 6 to US3.2bn for the six months to 30 September, with profit before tax down 21 to 517mln and earning per share falling to US0.335 from US56.5. 