The indigenous population has increased by 27% for male and by 42% for female since the implemation of Indigenous Status Act in 2001, in which the “surname-based status inheritance rule” was adopted and the descendents of approximately 20000 “Indigenous-wife and Han-husband” intermarried households who follow meternal surname can obtain Indigenous status. The purpose of this study is to analyze and compare the trends, seasonality, outliers and SARIMA models of the two time series of population. The method of time series analysis was adopted, utilizing the statistics released by the Ministry of the Interior.
The findings are as follows. First, the female series had higher increase rate, but had higher rate of slowing down; Second, the autocorrellation functions of female series are higher than male’s due to more increasing numbers, but seasonal autocorrellation functions are close to each other, reflecting the resembling periodical increase during the beginging of school semesters; Third, the outliers influenced by educational affirmative action reform of female series are much more obvious than male’s; Finally, both of the time series can be accurately forecasted with SARIMA(1,2,1)(2,1,0)12 model, but the seasonality of the forecasting numbers for female series is much more obvious than male’s.
The above differences are influenced by that female population increased far more than male’s, and the sex ratio for natural increase is 65 while 68 is for the status registrants. For the age group of 20~64, the registrant numbers about 16000 and 34000 were for males and females respectively; while 26000 and 28000 were for the age group of 1~19. It implies that the “surnamebased status inheritance rule” restricted the males’ status obtaining more than females’ for adults, but not so for younger generation.