The Role of Spectral Analysis in Time Series Analysis

Author(s):  
E. Parzen
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tanja Charles ◽  
Matthias Eckardt ◽  
Basel Karo ◽  
Walter Haas ◽  
Stefan Kröger

Abstract Background Seasonality in tuberculosis (TB) has been found in different parts of the world, showing a peak in spring/summer and a trough in autumn/winter. The evidence is less clear which factors drive seasonality. It was our aim to identify and evaluate seasonality in the notifications of TB in Germany, additionally investigating the possible variance of seasonality by disease site, sex and age group. Methods We conducted an integer-valued time series analysis using national surveillance data. We analysed the reported monthly numbers of started treatments between 2004 and 2014 for all notified TB cases and stratified by disease site, sex and age group. Results We detected seasonality in the extra-pulmonary TB cases (N = 11,219), with peaks in late spring/summer and troughs in fall/winter. For all TB notifications together (N = 51,090) and for pulmonary TB only (N = 39,714) we did not find a distinct seasonality. Additional stratified analyses did not reveal any clear differences between age groups, the sexes, or between active and passive case finding. Conclusion We found seasonality in extra-pulmonary TB only, indicating that seasonality of disease onset might be specific to the disease site. This could point towards differences in disease progression between the different clinical disease manifestations. Sex appears not to be an important driver of seasonality, whereas the role of age remains unclear as this could not be sufficiently investigated.


Author(s):  
Juan Juan Zhang ◽  
Sang-Yong Tom Lee

This article studies the role of international spillover of information and communication technology (ICT) in economic growth. We examine the performance of ten countries from 1982 to 1999. By empirically analyzing the relationship between total factor productivity (TFP) and domestic and foreign ICT investment with time series analysis tools, we find limited evidence that there exist international ICT spillovers for a group of countries. Further, we discuss the possible ICT policies to improve productivity and balance out a win-win situation for both ICT spillover sending and receiving countries.


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