Effect of credit card usage on consumption time series tests (2000-2024)

This research aims to examine the effects of credit card usage on household consumption trends in Turkey, covering the period between 2000 and 2024. The aim of the research is to reveal the extent to which credit cards affect individuals' spending decisions, beyond being just a payment tool, with scientific data. The main variables examined in this study consist of the KKART series, which reflects credit card expenditures, and the TUKETIM series, which expresses total final consumption expenditures. The relevant data were obtained from public authorities such as the Central Bank of the Republic of Turkey (CBRT), Turkish Statistical Institute (TUIK) and Banking Regulation and Supervision Agency (BDDK). First of all, the statistical properties of the data were defined, then ADF and PP analyses were performed within the scope of stationarity tests, and it was observed that the series became stationary at the first difference. The Toda-Yamamoto Granger Causality Test was applied through the VAR model established within the framework of time series analyses, and the results revealed that credit card usage has a one-way causal effect on consumption expenditures. This result reveals that credit card expenditures have a directing effect on consumption; on the other hand, it shows that consumption expenditures do not significantly affect credit card usage. The study also evaluated the direction and intensity of the relationship between the two variables with response functions and variance decomposition analyses, and determined a long-term equilibrium relationship with the cointegration test. The findings show that credit cards affect not only short-term consumption but also long-term consumption trends. However, it shows that consumption remains weak in determining credit card usage. In the theoretical part of the thesis, consumption theories, borrowing behaviors and the effects of financial instruments on individual decision processes were examined; the economic and psychological effects of credit cards on consumer behavior were discussed extensively. It was evaluated that structural conditions specific to the Turkish economy, income uncertainties and inflationary environment increased the demand for credit cards. The findings obtained reveal that individuals use credit cards not only for the convenience of payment, but also to meet their basic needs, solve liquidity problems and protect themselves from economic fluctuations. This situation increases the power of credit card systems to direct consumption behaviors; For policy makers, it shows that it is an area that should be monitored carefully within the framework of both financial stability and sustainable borrowing.