This paper examines some of the economic and econometric issues that arise in attempting to measure the degree of concentration in an industry and its dynamic evolution.We o¤er new measures of concentration over aggregated periods of time and provide a sound statistical basis for inferences. Concentration is one aspect of the problem of measuring “market power” within an industry. Modern econom...

methylene blue is widely used in various industrial branches. due to insufficient treatment, its occurrence in wastewater is frequently detected, which may result in serious environment problems to aquatic organisms. hydroponic experiments were conducted with rice seedlings (oryza sativa l. cv. xzx 45) exposed to methylene blue to determine the effective concentration using relative growth rate...