Internal (the consumer itself) and external factors influence the consumer to buy a product. It is these factors that can affect the length of time the consumer to buy a product. Time-to-event data analysis is the method to analyze the data when the response of interest is the time until some event occurs. The data to be analyzed is in the form of time, also called failure time or survival time. Cox regression model is a semiparametric regression models that are examining the relationship of independent variables with failure time (survival time). In addition to the estimated regression coefficients obtained, by using the Cox regression model approach, can also be estimated hazard ratio (HR) of two individuals with different covariates. This paper presented an examination of the use of Cox regression models to resolve problems related to consumer purchasing decisions. To clarify the exposure will be used simulated data and bootstrap resampling by using R software, where the response is examined is the time it takes the consumer to decide to buy a product is calculated from the first time consumers know the product, while the independent variables examined were level of education, occupation and monthly income of the consumer. Output program produces estimates of regression coefficients and standard errors of each coefficient. Interpretation of the hazard ratios for two covariates of each independent variable are presented in the discussion

The main product of mature coconuts is coconut meat, while its by-products consisting of coconut water, shell fiber and coir. Coconut coir contains 75% fiber and 25% cork. The high value of fiber in coconut coir provides an opportunity to be utilized in making paper. Coconut fiber has a cellulose content of 26.6%-43.44% and lignin of 29.4%-45.84%. Due to the high lignin content, delignification process should be carried out which can be done using sodium hydroxide (NaOH). This study aims to obtain the optimal point of addition of NaOH and cooking time to produce optimal cellulose and lignin levels in the delignification of the mature coconut fiber pulping process. The research method uses the Response Surface Methodology (RSM) with two factors and two optimized responses. The experimental design was performed with a central composite design. The variables involved were NaOH concentration (5-15%) and cooking time (90-150 minutes). Two responses studied were lignin and cellulose content. The combination of these treatments produces the optimum point of NaOH concentration of 5% and cooking time of 150 minutes, resulting in 15.56% lignin content and 37.29 % cellulose content.

Effect of Temperature Stress and Metal Ion Supplement on Ethanol Fermentation by Zymomonas mobilis

PT X Indonesia is one of the foreign companies from South Korea that engaged in producing additional ingredients for animal feed. Located in Pasuruan-East Java, PT X is one of the industries producing L-Lysine and L-Tryptophan essential amino acids. L-Lysine and L-Tryptophan products are stimulants for animal feed which are exported to several countries. The planning of the production process is based on requests from the headquarters of PT X Indonesia in South Jakarta, Indonesia. To meet the needs of export products to several countries, PT X requires careful planning in providing the products. One of the determining factors in planning and providing products accurately, effectively, and efficiently is demand forecasting. This study aimed to forecast the export demand of L-Lysine. Historical data used for forecasting was time-series data from September 2019 to January 2020. The best ARIMA model combination chosen for forecasting was (1,0,1) because both the p-values for the AR and MA models are significant and it has the smallest Mean Square Error (MSE). Forecasting results use the ARIMA model showed that L-Lysine export for four weeks was in a range of 2,596.47 tons to 2,597.5 tons with a total of 10,387.9 tons and an average of 2,596.975 tons per week.