JD Wetherspoon's first half sales are expected to be offset by a decline in margins as the pub operator lured in customers with cheaper drinks.Numis predicts pre-tax profit of £38.4m, up from the previous year's £37.8m. Like-for-like sales are projected to increase 4.8% but earnings before interest and tax (EBIT) margins are estimated to fall 90 basis points."Management strategy is built around growing cash profits/pub, rather than preserving margins," Numis said. "The outcome is an increasing drinks price discount to the industry (now at 17.6%, based on CGA data), an estimated 6% decline in H1 EBIT/pub and consensus forecasts falling by 4% since 1 January, versus a very slight overall increase for the peer group."The broker argued that given the improving consumer backdrop there could be a case of the company increasing prices slightly.In economic data, a report on UK construction output is due at 09:30 GMT with analysts expecting a 2.1% increase in January.The University of Michigan's consumer confidence index at 14:00 GMT is forecast to come in at a reading of 95.7 in March, up from the prior month's 95.4 amid an improving labour market and economy.Friday 13 MarchINTERIMSForte Energy NL, Wetherspoon (J.D.)INTERIM DIVIDEND PAYMENT DATEFusionex International, Murgitroyd GroupQUARTERLY PAYMENT DATECarnivalINTERNATIONAL ECONOMIC ANNOUNCEMENTSProducer Price Index (US) (12:30)U. of Michigan Confidence (Prelim) (US) (13:55)GMSStandard LifeFINALSOxford BiomedicaANNUAL REPORTJohnson Service GroupIMSSSThreeSPECIAL DIVIDEND PAYMENT DATEEntu (UK)AGMSChenavari Capital Solutions Limited Red, Hyundai Motor Company GDR (Reg S), LG Chem Ltd GDS (Reg S), Samsung C&T Corp. GDR, Samsung Electronics Co Ltd (ATT) GDR (Reg S)FINAL DIVIDEND PAYMENT DATEQatar Investment Fund, Zytronic