Business tendency surveys are commonly used to provide estimations ofa wide range of macroeconomic variables before the publication of official data. The qualitative nature of data on the direction of change has often led to quantifying survey results making use of official data, introducing a measurement error due to incorrect assumptions. Through Monte Carlo simulations it is possible to isolate the measurem.ent error introduced by incorrect assumptions when quantifying survey results. By means of a simulation experiment we check the effect on the measurem.ent error of respondents diverging from, 'rationality'. We also analyse the predictive performance of different quantification methods for fourteen EU countries and the euro area. We fmd that allowing for asymmetric and stochastic response thresholds (indifference interval) produces a lower measurement error and more accurate forecasts.