Eni Sumarminingsih was explaining the results of the research in her dissertation on the open session of the doctoral promotion in ITS Rectorate

ITS Campus, ITS News – The inflation value and the amount of money supply in the community are important and actual economic variables. This has triggered many researchers to develop methods and models to predict the change of the value, one of which is the doctoral program student from the Statistics Department of Institut Teknologi Sepuluh Nopember (ITS), Eni Sumarminingsih.

Through her dissertation entitled Spatial Vector Autoregressive Model with Calendar Variation and Its Application on Inflation Data and The Amount of Money Supply in Surabaya, Malang, Kediri, and Jember, Eni managed to earn her doctoral degree in open session of doctoral promotion in the Main Meeting Room of ITS Rectorate Building, Friday (30/8).

Previously, the candidate who was promoted by Dr. Ir Setiawan MS, Dr. Drs Agus Suharsono Ms, and Prof Dr. Budi Nurani Ruchjana MS had passed the dissertation session on August 16. The main point that she highlighted in her research was the application of a calendar variation to the developed model. Thanks to this research, Eni successfully graduated with a near-perfect GPA of 3.97.

Eni explained the calendar variation model itself consists of two types, namely trading day effect and holiday effect. Trading day effect is an effect caused by changes in the number of days a week in a month, while the holiday effect is the effect of a holiday or religious day. “This holiday effect is unique because there are certain religious holidays that are determined based on the month calendar so that the holidays occur on different dates and months each year,” she explained.

Eni Sumarminingsih during the discussion session in her doctoral promotion session at the ITS Rectorate

Through this research, Eni concluded that the model parameter estimator built with the calendar variation has efficiency and consistency. As for the application of SpVAR model with calendar variation in inflation data and money supply amount, it can be concluded that there is a relationship between inflation and money supply amount, as well as space and time relationship.

According to Eni, there was a significant correlation between inflation and money supply amount in the four cities that she researched. “As for the correlation between the inflation value and = money supply amount, the value is relatively small but still significant,” she said.

Eni explained, in addition to inflation data and money supply amount, the model she developed was also flexible enough to be applied to other issues that were equally influenced by the calendar variations, such as the value of train ticket sales. For example, ticket sales from Malang to Surabaya, the peak occurs on Monday. On the other hand, the train tickets from Surabaya to Malang are even more on Fridays.

Eni Sumarminingsih answered questions from examiners in her doctoral promotion session at the ITS Rectorate

“It means if within one month there are only five Monday, the ticket sales result for that month will be greater than the month that only has four days of Monday,” he explained.

The person who successfully graduated as a doctorate with a very satisfying predicate claimed to have uploaded her research in an international journal so that it can be applied at any time by those who need it.

The 31st doctorate from ITS Statistical hopes that in subsequent research, the Spatial Vector Autoregressive model can be developed with exogenous variables in the form of intervention variables or metric variables. “Besides, it is also necessary to develop SpVAR model for errors that do not have a normal distribution,” she concluded. (qi/gayatri/ ITS Public Relation)