Kısa dönem faiz modellerinin Türkiye için ampirik analizi

Faiz oranları finansal piyasalarda en fazla takip edilen ve öngörüsü yapılmaya çalışılan değişkenlerden biridir. Faiz ve faizin volatilitesi bir çok finansal enstrümanın fiyatlanmasında rol oynamaktadır. Bu ampirik çalışmada kısa dönem faiz modellerinden hangilerinin Türkiye için uygun olduğu tespit edilmeye çalışılmıştır. Bu amaçla kısa dönem risksiz faiz oranı olarak Türkiye Cumhuriyet Merkez Bankası gecelik faiz oranlarının aylık ortalaması kullanılmıştır. Veri seti Ocak 1990 ile Temmuz 2008 tarihleri arasını kapsamaktadır. Parametrelerin tahmininde değişkenlerin dağılım varsayımına ihtiyaç duymayan genelleştirilmiş momentler metodu kullanılmıştır. Tahmin sonuçları Cox Ingersoll Ross’un kare kök süreci ile Brennan-Schwartz modellerinin Türkiye için uygun olduğunu göstermiştir. Her iki modelin ortak noktası değişen varyans özelliğine sahip olmasıdır. Türkiye’de merkez bankasının politika değişikliğininin faiz süreci üzerinde etkisi araştırılmıştır. Yapısal değişmenin faizin volatilite sürecini etkilemediği buna karşılık faizin düzeyinin değişiminin etkilediği tespit edilmiştir.

An empirical analysis of short term interest rate models for Turkey

Interest rate is one of the most observed and forecasted variables in financial markets.Interest rates and the volatility of interest rates play a crucial role in pricing financial instruments.In this empirical study, we try to investigate which short term interest rate model is appropriate for Turkish data. In that regard we use monthly average of the central bank overnight interest rate. The date set covers the period from 1990:01 to 2008:07. We use the generalized method of moments to estimate the model parameters since it does not require a distributional assumption for the interest rate making GMM a robust estimation method comparing to maximum likelihood. Estimation results reveal that Cox Ingersoll Ross square root process and Brennan-Schwartz models perform better. A common feature of these models is that they both have heteroscedastic variances. In the study, we also analyzeif the policy changes of Central Bank of Turkey had any effects on the interest rate process.We find that the volatility of the interest rate is not affected by policy change. However, the level of the interest rate is affected.

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