生育率的降低是影響台灣地區近年來人口老化的顯著因素，因其變化幅度通常高於死亡率，對人口結構的影響較大。過去台灣地區生育率研究多為整體生育(如：總生育率、年齡別生育率)趨勢的模型，較少探討台灣各地區的特色。為能更深入瞭解台灣生育行為變化的特性，本文將生育率的研究層面由整體的資料，延伸至全台灣地區的各鄉鎮市區（不含離島地區有350個鄉鎮市區），希冀能更精確地找出與台灣地區生育率持續下降的相關因素。本文分為兩個部份，以鄉鎮市區的年齡別婦女生育率與年齡別有偶婦女生育率為研究對象，資料時間為1991、1992、2001、2002年：第一部份探討各鄉鎮市區的生育率數值間是否存在空間相關性，並進一步瞭解生育率較高（或較低）的地區是否有聚集的現象。第二部份則套用空間迴歸模型探討與生育率數值有關的因素（例如：人口密度、教育程度等），更精確且客觀地提供生育率未來趨勢的建議。 關鍵字：生育率、人口老化、空間統計、空間群聚、空間迴歸 / Both the fertility rates and mortality rates, especially the fertility rates, have been experiencing dramatic decreases in recent years, and the population aging thus has become one of the major concerns in Taiwan area. In order to identify the factors that are related to the decrease of fertility rates, unlike the previous works that deal with the aggregate national data, we will study the fertility pattern in township level. We will use the data of age-specific fertility rates and total fertility rates in 1991, 1992, 2001, and 2002 in 350 townships of Taiwan area. This study will be separated into two parts. First, we shall explore if there is spatial correlation among 350 townships of Taiwan area and detect if there are spatial clusters for higher fertility townships. The second part of this project will be focused on the spatial regression model. We will use this model to determine the factors that are highly correlated to the dropping of fertility rates. Key Words: Fertility Rates, Aging Population, Spatial Statistics, Spatial Clustering, Spatial Regression

近年來國人晚婚、不婚、晚育或不育的現象持續惡化，衍伸出高齡少子化所帶來之人口結構惡化已是國家安全層次議題。本研究以實證方式探討影響台灣地區生育率之主要因素，並著重住宅價格（房價所得比）、住宅交易數量（建物買賣移轉棟數）及存量（自有住宅率）之變化與總生育率之關聯性。探究近年我國房價變化、持有自有住宅比率及住宅市場之交易活絡程度是否會影響家戶單位生育決策。 研究針對西元2002年至西元2015年間台灣地區20縣市共280筆追蹤資料(Panel data)，在控制時間效果下運用傳統最小平方法、固定效果模型及隨機效果模型對資料進行迴歸分析。研究結果顯示：在考慮生育率落後一期情境下，同時控制時間及區域效果模型中發現：房價所得比與總生育率呈現顯著正相關，建物買賣移轉棟數與總生育率呈現顯著負相關，自有住宅率雖與總生育率為正相關但未達顯著水準。而其他影響總生育率之主要變數：女性受高等教育比率及粗結婚率與總生育率成顯著正相關。失業率與總生育率則為顯著負相關。研究結果可發現，可能由於我國高度自有住宅率之特性，房價上漲帶來之財富效果是導致房價所得比與生育率呈現正向關係之成因。建物買賣移轉棟數與總生育率呈現負向關係，研判來自於家戶購屋初期通常需付出一筆為數不小之頭期款，短期間內將耗用家戶較多經濟資源，進而排擠家戶單位短期生育決策。 / In recent years, more and more Taiwanese tend to marry at a later age, or remain unmarried, or bear children at a later age or not at all. The problems of population aging and low birth rate have led to the worsened population structure, which has become an issue of national security. This empirical study investigated the factors that contributed to the present low birth rate in Taiwan. The study emphasized the relationships between housing price to income ratio, the number of housing transferred, homeownership rate and total fertility rate (TFR). This study also tried to investigate how the aforementioned three factors affect the childbearing decision of family units. The study focused on a panel data set with 280 samples that was collected across 20 cities and counties in Taiwan from 2002 to 2015. Ordinary least squares, fixed effects model and random effects model were used, and time effect are controlled in all models. The results showed that, after controlling for the time and regional effects, the housing price to income ratio had a positive relationship with the lag TFR. The number of building transferred had a negative relationship with the lag TFR. The homeownership rate had an insignificant negative relationship with the lag TFR. Other factors also affected the lag TFR. For example, the ratio of females who received higher education and crude marriage rates had a significant positive effect. The unemployment rate had a significant negative relationship with the lag TFR. The results might imply that, given the high homeownership rate in Taiwan, the rise in housing price increase “wealth effect’’ which is the reason for the positive relationship between housing price to income ratio and lag TFR. The reason for the negative relationship between the number of building transferred and lag TFR could be the huge financial burden of down payment when a family purchases a house. This burden takes out a huge portion from the budget, and therefore family units might decide to delay having children for a short period.

人口政策是政府的重要政策之一，而總人口數則是政府制定政治、經濟、社會及文化發展計畫之主要參考依據，因此如何準確地預測未來的總人口數就成為政府相關部門重要的課題。 本論文試圖為台灣地區總人口數建立時間數列預測模式。我們考慮下列模式：單變量自我迴歸整合移動平均介入模式、時間數列迴歸模式、轉換函數介入模式與指數平滑法，其中轉換函數介入模式中所考慮的投入變數包括育齡婦女總生育率、粗出生率及粗死亡率。我們同時以平均絕對百分誤差 (MAPE) 、根均方百分誤差 (RMSPE) 來評估各模式的預測能力，結果顯示以育齡婦女總生育率為投入變數的轉換函數介入模式最佳，而以粗出生率為投入變數的轉換函數介入模式次之，若以這兩個模式進行未來十年總人口數之預測，並與行政院經建會人力規劃處所作的人口預測中推計值比較，其平均絕對百分誤差分別為0.138%，0.156%，顯示時間數列預測模式有相當佳的預測能力。 / In this thesis, we plan to construct various time series models for the total population in Taiwan. The following time series models are considered: ARIMA intervention model, time series regression model, transfers founction intervention model and exponential smoothing method. The input variable considered in the transfer function intervention model include total fertility rate, crude birth rate and crude death rate. We also compare the prediction performance of these models by using mean absolute percentage error (MAPE) and root mean square percentage error (RNSPE). It turns out that the transfer function intervention model with total fertility rate as input is the best model. While the transfer function intervention model with crude birth rate as input ranks the second best. Finally we forecast the total population of the next ten years by using the above two best models and compare with the middle population projection by Manpower Planning Department in Executive YUAN-Council for Economic Planning and Development. The mean absolute percentage error are 0.138% and 0.165% respectively. This result justifies that the time series model has excellent predictive ability and should be considered for total population prediction.

台灣地區的人口隨著生育率及死亡率的雙重下降而呈現快速老化，其中生育率的降低影響尤為顯著。民國50年時，台灣平均每位婦女生育5.58個小孩，到了民國70年卻只生育1.67個小孩，去年（民國90年）生育率更創歷年新低，只有1.4。死亡率的下降可由平均壽命的延長看出，民國75年時男性為70.97歲，女性為75.88歲；到了民國90年，男性延長到72.75歲，女性延長到78.49歲。由於生育率的變化幅度高於死亡率，對人口結構的影響較大，因此本文分成兩個部份，主要在研究台灣地區15至49歲婦女生育率的變化趨勢，再將研究結果用於台灣地區未來人口總數及其結構的預測。 　　本研究第一部分是生育率的研究，引進Gamma函數、Gompertz函數、Lee-Carter法三種模型及單一年齡組個別估計法，以民國40年至84年（西元1951年至1995年）的資料為基礎，民國85年至89年（西元1996年至2000年）資料為檢測樣本，比較模型的優劣，尋求較適合台灣地區生育率的模型，再以最合適的模型預測民國91年至140年（西元2002年至2051年）的生育率。第二部分是人口推估，採用人口變動要素合成方法（Cohort Component Projection Method）推估台灣地區未來50年的人口總數及其結構，其中生育率採用上述最適合台灣地區的模型、死亡率則引進國外知名的Lee-Carter法及SOA法（Society of Actuaries），探討人口結構，並與人力規劃處的結果比較之。 / Both the fertility rate and mortality rate have been experiencing dramatic decreases in recent years. As a result, the population aging has become one of the major concerns in Taiwan area, and the proportion of the elderly (age 65 and over) increases promptly from 2.6% in 1965 to 8.8% in 2001. The decrease of fertility rate is especially significant. For example, the total fertility rate was 5.58 in 1961, and then decreases dramatically to 1.67 in 1981 (1.4 in 2001), a reduction of almost 70% within 20 years. 　　The goal of this paper is to study the population aging in Taiwan area, in particular, the fertility pattern. The first part of this paper is to explore the fertility models and decide which model is the most suitable based on age-fertility fertility rates in Taiwan. The models considered are Gamma function, Gompertz function, Lee-Carter method and individual group estimation. We use the data from 1951 to 1995 as pilot data and 1996 to 2000 as test data to judge which model fit well. The second part of this study is to project the Taiwan population for the next 50 years, i.e. 2002-2051. The projection method used is Cohort Component Projection method, assuming the population in Taiwan area is closed. We also compare our projection result to that by Council for Economic Planning and Development, the Executive Yuan of the Republic of China.

京都大学 / 0048 / 新制・課程博士 / 博士(法学) / 甲第19948号 / 法博第193号 / 新制||法||156(附属図書館) / 33044 / 京都大学大学院法学研究科法政理論専攻 / (主査)教授 稲森 公嘉, 教授 村中 孝史, 教授 潮見 佳男 / 学位規則第4条第1項該当 / Doctor of Laws / Kyoto University / DGAM