A Time Series Analysis of Student Credit Card Charges (2012–2013)



 The time series plot shows student credit card charges from January 2012 to December 2013. Charges generally increased over the two years, with noticeable rises during the summer and at the end of each year, likely reflecting holiday periods and the start of the school year. This suggests students tend to spend more during these predictable seasonal peaks.

The Exponential Smoothing (ETS) model was applied to the combined data and selected ETS(M,N,N), which means a multiplicative error with no trend and no seasonality. The smoothing parameter α = 0.8635 indicates that the model gives relatively high weight to recent observations. The initial level (l) is 30.9107, and the model’s sigma (standard deviation of the residuals) is 0.1354. The fitted values closely follow the actual charges, showing that the ETS model effectively captures the upward trend and smooths out month-to-month fluctuations.

Overall, the time series plot and ETS model together reveal a consistent increase in student spending over the two years, with predictable patterns that could help anticipate future charges.


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