Implementation of the Bisection Method to Determine the Year Predicted Open Unemployment Rate Will Reach 5% in Central Java Province Based on Data for 2018 – 2024

Abstract

This study is motivated by the importance of predictive analysis of the open unemployment rate  as an indicator of employment conditions. Most previous studies tend to focus on modeling without determining the time to achieve a certain value. Therefore, this study aims to predict the year when the TPT in Central Java Province will reach 5%, by applying a two-part method based on Microsoft Excel. The methodology used is a quantitative approach with a descriptive-analytical design. The data analyzed is secondary data on the TPT in Central Java Province for the period 2018–2024, sourced from the Central Statistics Agency. Data collection was carried out through documentary studies, while data analysis included descriptive analysis, polynomial regression modeling, and the iterative application of the bisection method using Microsoft Excel. The results showed that the second-order polynomial regression model successfully represented the data with a coefficient of determination of 0.629. The implementation of the bisection method produced an estimated root of 6.524713, in a stable and convergent iteration process until it reached a very small error. These findings indicate that the TPT is predicted to reach 5% between mid-2024 and early 2025. This study implies that the integration of regression and Excel-based numerical methods can be a systematic, practical, and easily replicable approach in the analysis of employment indicator predictions.