Mathematical models 869 Congresses 204 Economic conditions 102 Econometric models 84 Data processing 83 Economics 61 Economic policy 59 Simulation methods 59 Computer simulation 42 Economic aspects 40 City planning 38 Research 36 Econometrics 33 Economic development 32 Education 31 Pollution 31 Regional planning 31 Evaluation 28 System analysis 28 Macroeconomics 27 Transportation 27 Decision making 26 Digital computer simulation 26 Management 26 Mathematics 26 Decision-making 25 Hydraulic models 24 Accounting 23 Agriculture 23 Computer programs 23