Methods 683 Studies 331 Methode 297 Analysis 178 Wissenschaft 155 Qualitative methods 134 Research 97 Usage 94 Quantitative methods 90 Theorie 87 Environmental Monitoring - methods 74 Politische Wissenschaft 71 Journal Article 67 Economic models 63 Research Methodology 58 Water Purification - methods 55 Generalized method of moments 51 Politics 51 Population 49 Wissenschaftliche Methoden 48 Social aspects 46 Wissenschaftliche Methode 46 Political science 45 Evaluation 43 Forecasts and trends 43 Observations 43 Demographic Factors 42 Economic aspects 41 Analyse 39 Water Pollutants, Chemical - isolation & purification 39