eng Science and Education Publishing Journal of Finance and Economics 2328-7276 2020-04-05 8 2 61 68 10.12691/jfe-8-2-3 JFE2020823 article Iman Firmansyah firmansyah1958@yahoo.co.id 1 Edi Gunadi 1 Department of Industrial Engineering, Universitas Pasundan, Bandung, Indonesia The Indonesian government uses the exchange rate of US dollar (USD) as an indicator in the preparation of the Draft of State Revenue and Expenditure Budget (RAPBN). The reason is that the daily exchange rate of the US dollar is a time series data with significant autocorrelation. Although the variance is relatively small, it cannot be considered constant. So, that the functional relationship model of the variants needs to be examined in addition to the functional relationship model of the exchange value. The study of the functional relationship model of observational values and their variants can simultaneously be analyzed by ARCH model based on daily data between 1 July 2015 - 31 July 2019. http://pubs.sciepub.com/jfe/8/2/3/jfe-8-2-3.pdf ARCH model constant variant foreign exchange rate Rupiah US dollar