Penerapan Statistical Quality Control dalam Menganalisis Kualitas Air Sungai Oya di Daerah Istimewa Yogyakarta

Abstract

The quality of river water in Indonesia is mostly in a heavily polluted condition, so it is very concerning considering that river water is the main source of clean water used by the majority of Indonesia's population. The poor quality of river water will threaten the health conditions of residents and other living things around the river area. This final project aims to determine whether the water quality of the Oya river is within control limits or not and to analyze whether the water quality of the Oya river in Daerah Istimewa Yogyakarta requires increased cleanliness around the river. To see the control limits for each river water quality, the method used is statistical quality control (SQC). Thus, if we look back at the observation results for the X-bar, Range and Standard Deviation control charts, there is one variable that is out of the upper or lower control limits. By conclusion, the mean value which is the median line for the x control chart on the water quality of the Oya River is 1625.7068. The upper control limit (BKA) is 4212.6057, and the lower control limit (BKB) is -961.1921. Indicates that there is a water quality in the Oya river that is outside the control limits, namely Koli Tinja (MPN/100 ml). The average value which is the center line for the R control chart on the water quality of the oya river is 3550.5200. The upper control limit (BKA) is 8102.4697, and the lower control limit (BKB) is 0. This indicates that the water quality of the Oya River is outside the control limit, namely Koli Tinja (mpn/100 ml). The average value is the middle line. for the S control chart on the water quality of the oya river is 1577.2638. The upper control limit (BKA) is 3574.1539, and the lower control limit (BKB) is 0. This indicates that the quality of the Oya river water is outside the control limit, namely Koli Tinja (MPN/100 ml). With several variables that are still outside the control limits indicating that the results are not in accordance with control standards