2001年實施的《原住民身分法》改採「從姓原則」，使當時約2萬原妻漢夫通婚戶後裔取得身分認同權，而男、女性人口數至2015年底也各增27%、42%。本研究目的為分析並比較兩性原住民人口時間序列的趨勢性、季節性、離群值及預測模式。研究方法採時間序列分析，研究資料取自內政部2001～2016年歷月原住民人口統計數。本研究發現，女性序列增幅大於男性，但增幅減緩程度也大於男性；其次，雖然女性序列因月增數持續較多而自相關較高，但反映每年學校開學期間人口增加較多的季節性自相關兩性相當；第三，《原住民身分法》頒行與升學加分改制等外部事件使女性序列離群值較多；最後，兩個差分後的定態序列再排除離群值影響，皆可配適SARIMA(1,2,1)(2,1,0)12模式，女性預測結果因月增數仍較多使季節性較明顯。為瞭解上述差異之構成，綜合政府統計資料估算出原住民人口自然增加性別比為65、登記身分人數性別比為68；男、女性登記身分人數在20～64歲各約1.6、3.4萬人，在1～19歲各增2.6、2.8萬人，可見「從姓原則」對成年男性取得身分的約制作用大於女性，但對兒少人口影響小很多。

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.