Farida Agustini Widjajati
Institut Teknologi Sepuluh Nopember

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Journal : International Journal of Computing Science and Applied Mathematics-IJCSAM

Optimizing Forest Sampling by using Lagrange Multipliers Suhud Wahyudi; Farida Agustini Widjajati; Dea Oktavianti
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 3 No. 2 (2017)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

To obtain information from a population, we use a sampling method. One of sampling techniques that we can use is double sampling. Double sampling is a sampling technique based on the information of first phase which is used as an additional information obtaining estimates for the second phase. In this case, we discuss the model of double sampling with regression estimator. Then, to obtain the optimal number of samples for the first and second phases, we use Lagrange multipliers. The model analysis result is a formula to calculate the optimal number of samples for the first phase (n0) and the second phase (n1). Implementation of this method is simulated by using teak stands data from previous studies at Forest Management Unit (FMU) Madiun which consists of Section Forest Management Units (FSMU) Dagangan and Dungus. The calculation result of data from FSMU Dagangan, we get optimal number of plots must be observed in image interpretation are 149 plots and field survey are 14 plots. And with the data from FSMU Dungus, we get optimal number of plots to be observed in image interpretation are 153 plots and field survey are 20 plots.
Quality Control Analysis of The Water Meter Tools Using Decision-On-Belief Control Chart in PDAM Surya Sembada Surabaya Farida Agustini Widjajati; Nuri Wahyuningsih; Lisda Septi Hasofah
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 2 No. 1 (2016)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Efforts to maintain and improve the quality of the resulting product can be done by using statistical quality control. One of the methods used in quality control is DOB (Decision On Belief) control chart. DOB control chart is a controller diagram which is used in quality control of univariate data. In this paper, we discuss quality control of the water meter tools using DOB control chart. The case study is in PDAM Surya Sembada Surabaya. Production quality control can also be applied to the c univariate control chart to compute the sensitivity of DOB control chart. Implementation of c control chart and DOB control chart indicates that the data of water meter tools have not been statistically controlled. Application of DOB control chart provides results that are more sensitive by 23.33% than c control chart based on the amount of data that is out of control.