In this chapter some typical methods of statistical inference are presented in order to analyse results of investigations of economic conditions based on questionnaires. One considers variation in the structure of answers between particular questions, within particular groups of questions, between particular groups (subpopulations) of enterprises and within the subpopulations. One also shows a way to analyse variation of the balance of answers (i. e. the difference between the fractions "increase" and "decrease") with respect to time. The methods are the well-known Pearson's chi-square test and a test based on the asymptotic normal distribution. Finally, one addresses the problem of Bayesian analysis of the business activity results by demonstrating some simple estimation and testing procedures. The data come from the database of IRG SGH (Institute of Economic Development, Warsaw School of Economics).