Yen

The Forex market is known as the strongest and richest financial market in the world that has been operating continuously. This market is formed based on the exchange rates of different countries, as well as the prices of oil and gold. The price of currency pairs in the Forex market as the largest market for financial transactions has always been of great importance. The purpose of this article is to study the Forex market based on chaos theory. Its statistical population includes three currency pairs Euro / Dollar, Pound / Dollar and Dollar / Yen. The period of prices of the surveyed currency pairs is from January 2017 to December 2021 and its time range includes daily prices. The results showed that after fitting the model and performing the BDS test, on the GARCH model residues in different dimensions and ε of all 6 groups, which are IID residues and there is no dependence on them. The results of Lyapunov's maximalism test showed that for all dimensions, and all time intervals (n), the value of Lyapunov's exponent is a positive and small number, indicating that the time series of the triple currency pair follows a chaotic process.

Testing organizations are faced with increasing demand to provide subscores in addition to the total test score. However, psychometricians argue that most subscores do not have added value to be worth reporting. To have added value, subscores need to meet a number of criteria: they should be reliable, distinctive, and distinct from each other and from the total score. In this study, the quality of subscores from two subscore augmentation models (Wainer and Yen) were compared in terms of distinctness and variability. The reliabilities of the Wainer-augmented subscores were also examined. The models were applied to a high-stakes English language proficiency test in Iran. The results of the study showed that Yen better satisfied subscore distinctness while Wainer best preserved variability and had high-reliability subscores. In other words, Yen-augmented subscores had lower correlations while Wainer-augmented subscores better discriminated examinees with different ability levels. Thus, none of the examined models of subscoring satisfied all criteria. The results of the study are discussed and suggestions for future research are provided.