Application of mixed effects model in experimental design in production sector

In the production line of the factories, raw materials are processed through various processes and turned into semi-finished and final products, and during production, quality control and inspection processes aim to ensure that the products comply with the standards. Customer satisfaction, quality and high efficiency are targeted at every stage of production. For high efficiency, the most suitable conditions for production are provided by taking into account the factors in the production line and the levels of these factors. Obtaining appropriate conditions during the production process is critical for the efficiency of the factory and product quality. Ensuring high efficiency with product quality is achieved by controlling the temperature, humidity and hygiene conditions of the environment, regular maintenance, calibration of the machines, and compliance of the employees with occupational health and safety rules. Thus, high quality and standard compliant products are obtained without any disruptions during production. In this study, the effects of temperature and humidity rates in the mold heating and mold cooling cabins on the chocolate production line in a factory on the scrap rate in production were investigated. Ambient temperature and humidity data in mold heating and mold cooling cabins obtained from sensors were used as a data collection tool. Mixed Effects Models were used as statistical analysis. The purpose of this research is to determine the effects of humidity and temperature in the production line on the reject rate. Keywords: Experimental design, Production, Multi-factorial experiments, Mixed effects model