Mekânsal Veri Analizi Teknikleriyle Türkiye’de Toplam Doğurganlık Hızının Dağılımı ve Modellenmesi
Türkiye’de doğurganlık geçmiş kırk yılı aşkın bir sürede, hızlı ve bir geçiş oluşturacak şekilde düşmüştür. Ancak doğurganlık, bölgesel düzeyde farklılıklar göstermekte ve Türkiye’nin batısı düşük doğurganlık düzeyine eriştiği halde, doğusu ve güneydoğusu, eğitim düzeyinin düşüklüğü ve etno-kültürel farklılıklara bağlı olarak hâlâ orta ve yüksek düzeyli doğurganlıklar sergilemektedir. Türkiye’de toplam doğurganlık hızının mekânsal örüntüsüne odaklanan bu çalışmada, doğurganlık hızına etki eden bazı ekonomik ve sosyo-kültürel değişkenler kullanılarak mekânsal veri analizi teknikleri yardımıyla mekânsal verinin gösterimi, araştırılması ve modellenmesi gerçekleştirilmiştir. Çalışmanın bulguları, Moran’s I saçılma grafiğine göre Türkiye’de toplam doğurganlık hızının yüksek-yüksek (YY) ve düşük-düşük (DD) olarak iki grupta yer aldığını ortaya koymaktadır. Yerel mekânsal oto-korelasyon (LISA) sonuçları, Türkiye’nin Doğu ve Güneydoğu Anadolu bölgelerinde pozitif, Marmara, Ege, Batı Karadeniz ve Orta Anadolu bölgelerinde negatif yönde bir mekânsal oto-korelasyonun olduğunu göstermektedir. Çalışmada iki regresyon modeli En Küçük Kareler Yöntemi (OLS) ve Coğrafi Ağırlıklı Regresyon (GWR) uygulanmış ve sonuçları karşılaştırılmıştır. Coğrafi Ağırlıklı Regresyon (GWR) modelinin, %93 oranında bağımlı değişkenin varyasyonlarını açıkladığı ve elde edilen sonuçlara göre, Türkiye’de toplam doğurganlık hızını modellemede başarılı olduğu gözlenmiştir. Aynı zamanda okur-yazar olmayan kadın oranı ve Kürt kökenli kadın oranı değişkenleriyle, toplam doğurganlık hızının yüksek olduğu yerlerde gerçeğe yakın ölçüm sonuçlarını gösteren bir model elde edilmiştir. Bu çalışma, mekânsal veri analizi yöntemlerinin sosyo-demografik çalışmalara farklı bir bakış açısı sağlaması nedeniyle önem taşımaktadır.
Spatial Distribution and Modelling of the Total Fertility Rate in Turkey Using Spatial Data Analysis Techniques
The fertility rate has been declining for over four decades in Turkey. However, the fertility rate has shown regional variability due to ethno-cultural differences. While the fertility rate is low in the Western part of Turkey, the Eastern and Southeastern parts have still shown moderate to high rates. This study focuses on the spatial patterns of the total fertility rate. Using variables that may affect the fertility rate, such as economic and socio-cultural parameters, we performed spatial data analysis techniques to represent, analyze, and model the spatial data. The results show that according to Moran’s scatter plot, Turkey’s total fertility rate falls into two groups: high-high and low-low. On the other hand, local Moran’s I results have shown that while the East and Southeastern regions have positive auto-correlations, Marmara, the Aegean, the West Black Sea, and the Middle Anatolia regions have negative autocorrelations. In this study, we applied both the ordinary least square (OLS) and geographically weighted regression (GWR) models and compared the results. In GWR analysis, variance of the dependent variable was shown to be 93%, and we achieved a high success rate in modeling Turkey’s total fertility rate. In the limitation of this study, using an illiterate female population rate and Kurdish female population rate variables, one can obtain more accurate models that show the total fertility rate and show where the fertility rate is high. As a conclusion, spatial data analysis methods bring a new perspective to sociodemographic studies.
Recently, the number of studies frequently using statistical techniques, and software designed for geo-referenced data, and spatial analysis in many disciplines of social sciences has increased. Because of this increase, both geographers and demographers focus on the importance of spatial data analysis and the implementation of these methods in demographic studies, including fertility. Fertility has been dropping abruptly to form a transition for forty years in Turkey. At the regional level, while Turkey’s Western part has shown low fertility, the Eastern and Southeast regions, on the other hand, have not shown a significant fertility transition, and they have revealed high fertility levels, depending on the impairment and ethnic differences in the level of education. The aim of this study is to figure out the spatial patterns of the total fertility rate in Turkey, using economic and socio-cultural variables (non-literate female ratio (%), an undergraduate female ratio (%), a female wageworker ratio (%), gross national product per capita (US dollars), an urbanization score with demographiceconomic-social variables, the female Kurdish population rate (%), the Kurdish population rate (%), the female Arabic population rate (%), the number of medical doctors per person, and the average life span (years) that affecting the fertility rate. To achieve this, the spatial data were arranged, investigated, and modeled via spatial data analysis techniques. By taking into account fertility related variables, correlation analysis was performed. The ratio of non-literate women and the proportion of Kurdish women showed a high positive correlation. Different spatial weight matrices (spatial weight matrix) were created to investigate the distribution of data in the study. Moran’s I and Z values were taken into consideration, and a fixed distance of 200 km was specified for use in weight matrix analysis. A global autocorrelation (Global Moran’s I) graph was measured as 0.7836. According to the Moran scatter plot, the total fertility rate in Turkey is split into two groups: either high-high (YY) or low-low (DD). According to local indicators of spatial associations results, Northeast Anatolia, Central East, and Southeast Anatolia have a positive spatial autocorrelation, whereas in Istanbul, West Marmara, East Marmara, West Anatolia, the Aegean, and Mediterranean regions have a negative spatial autocorrelation. Next, two regression models, the ordinary least square (OLS) and geographically weighted regression (GWR), were compared. The values of Akaike’s information criterion (AIC) and the adjusted R2 were measured as 73.64 and 0.90, respectively. The AIC value is 63.08 and the adjusted R2 value is 0.93 in GWR analysis. The GWR model was able to explain 93% of the variants of the dependent variable. This study has clearly shown the difference in the spatial patterns of fertility in Turkey. It also shows that the relationship between the total fertility rate and sociodemographic variables can be explained using spatial data analysis methods. The GWR model gave the most accurate results in places where the ratio of non-literate women and Kurdish women, closely related to the total fertility rate, were high. According to the results, there is a positive relation between the rate of illiterate women and the total fertility rate. In other words, as the rate of illiteracy increases, there is also an increase in the total fertility rate. This feature prevails in Turkey’s Eastern and Southeastern regions. The fact that the literacy rate is very low for women clearly shows that there is gender discrimination in these regions. The negative relationship between fertility and education level shows that as the education level increases, there is a decrease in the total fertility rate. Women living in urban areas are more educated than the ones living in rural areas in Turkey. This situation results in a decrease in the fertility levels of women living in urban areas. On the other hand, as the proportion of women with Kurdish origin increases, total fertility rate increases. These results, showing the relationship between ethnicity and the total fertility rate, point out that a woman’s fertility is a criterion for acceptance by the community where the heavily Kurdish origin populations live. As a result, the habitat shapes individuals. Displaying spatial data analysis methods using socio-demographic indicators, aside from merely discussing these effects, gains a different point of view to this study.