پاندمی کووید 19، شاخص دلار آمریکا و قیمت بیت‌کوین: شواهدی از روش تحلیل موجک

نوع مقاله : مقاله علمی پژوهشی

نویسندگان

1 دانشجوی دکتری، گروه توسعۀ اقتصادی و برنامه‌ریزی، دانشکده مدیریت و اقتصاد، دانشگاه تربیت مدرس، تهران، ایران.

2 استادیار، گروه علوم اقتصادی، دانشگاه کردستان، سنندج، ایران.

3 کارشناس ارشد، گروه علوم اقتصادی، دانشکده علوم انسانی و اجتماعی، دانشگاه کردستان، سنندج، ایران.

10.22059/frj.2024.361672.1007484

چکیده

هدف: در اواخر سال ۲۰۱۹، جهان با چالشی بی‌سابقه مواجه شد. بحران کووید ۱۹ همۀ اقتصادهای توسعه‌یافته و درحال‌توسعه را تحت تأثیر قرار داد و در عین حال، بازارهای مالی بین‌المللی را به‌شدت محدود کرد. همان‌طور که کشورها به اجبار، قرنطینۀ سراسری را اجرا کردند، بازارهای مالی بسته شدند و هزینه‌های مراقبت‌های بهداشتی افزایش و رشد اقتصادی تا حدی کاهش یافت. ارزهای دیجیتال به‌طور چشمگیری تحت تأثیر بیماری کووید ۱۹ قرار گرفتند. کووید ۱۹ تنها دلیل افزایش قیمت بیت‌کوین نبود؛ اما شاید به‌دلیل افزایش عدم‌اطمینان و خطر در طول همه‌گیری جهانی، در افزایش این ارز دیجیتال نقش مهمی ایفا کرد. این پژوهش با استفاده از تبدیل موجک پیوسته (CWT) با هدف بررسی تأثیر کووید ۱۹ و شاخص دلار آمریکا بر قیمت بیت‌کوین، در تاریخ ۸ آوریل ۲۰۲۰ تا ۸ آوریل ۲۰۲۳ انجام شده است. در حالی‌که پژوهش‌های محدودی در زمینۀ این موضوع انجام شده است؛ این پژوهش به‌دلیل استفاده از تبدیل موجک پیوسته، ضمن داشتن نوآوری، مزیتی نسبت به سایر پژوهش‌های انجام شده در این حوزه دارد.
روش: در این پژوهش، رویکرد موجک برای تحلیل تأثیر زمان – فرکانس پاندمی کووید ۱۹ و شاخص دلار آمریکا بر قیمت بیت‌کوین استفاده شده است. روش تبدیل موجک پیوسته، بر اساس مطالعۀ گنجای و همکاران (۲۰۰۲) ارائه و طیف توان موجک متقاطع بین سری‌های زمانی مختلف محاسبه شده است. انسجام مربع موجک که بین صفر (ناهم‌بسته) و یک (کاملاً هم‌بسته) است، به همراه شبیه‌سازی مونت‌کارلو، برای تعیین اهمیت آماری و تحلیل وابستگی‌های زمانی ـ فرکانسی به‌کار رفته است. در دو مرحله، ابتدا رابطۀ قیمت بیت‌کوین با تعداد مبتلایان، مرگ‌ومیر کووید ۱۹ و شاخص دلار آمریکا بررسی شده و پس از آن، از انسجام موجک جزئی برای تحلیل وابستگی‌های بیشتر استفاده شده است.
یافته‌ها: یافته‌های پژوهش از تأثیر مثبت تعداد مبتلایان و مرگ‌ومیر ناشی از ویروس کرونا بر قیمت بیت‌کوین، طی دورۀ پژوهش حکایت می‌کند. این در حالی است که تأثیر تعداد مبتلایان، بیش از تأثیر تعداد کشته‌شدگان است. دلیل اصلی این امر می‌تواند افزایش عدم‌اطمینان و ریسک در طول همه‌گیری و افزایش تقاضای بیت‌کوین توسط سرمایه‌گذاران برای محافظت از ثروت و دارایی‌های خود باشد. از سوی دیگر، شاخص دلار آمریکا در دورۀ پژوهش، بر قیمت بیت‌کوین تأثیر منفی و معناداری داشته است که می‌تواند نشئت‌گرفته از جایگزینی دو کالا به‌عنوان پول باشد.
نتیجه‌گیری: بر اساس نتایج پژوهش، تعداد مبتلایان و تعداد مرگ‌ومیر ناشی از ویروس کووید ۱۹ در هر میلیون نفر، بر قیمت بیت‌کوین در بازۀ زمانی پژوهش، تأثیر مثبت و معناداری دارد. دلیل اصلی این تأثیر مثبت را می‌توان در فشار تقاضای ناشی از وجود ریسک و نااطمینانی سرمایه‌گذاران در یافتن سرمایه‌گذاری امن و افزایش تقاضای بیت‌کوین، به‌عنوان یک نوع دارایی امن دانست. از طرف دیگر، شاخص دلار آمریکا به‌عنوان رقیب کالایی بیت‌کوین، دارای تأثیر منفی و معنادار بر قیمت این ارز دیجیتال در دوره زمانی پژوهش است. دلیل اصلی این امر نیز می‌تواند در جانشینی دو ارز نسبت به هم دانست؛ زیرا هنگامی که ارزش دلار آمریکا روبه‌افزایش بوده، قیمت بیت‌کوین روند کاهشی به خود گرفته است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The COVID-19 Pandemic, the US Dollar Index, and Bitcoin Prices: Evidence from the Wavelet Analysis Method

نویسندگان [English]

  • Ramin Amani 1
  • Saman Ghaderi 2
  • Zanko Ghorbani 3
1 Ph.D. Candidate, Department of Economic Development and Planning, Faculty of Management and Economics, Tarbiat Modares University, Tehran, Iran.
2 Assistant Prof., Department of Economics, University of Kurdistan, Sanandaj, Iran.
3 M.Sc., Department of Economics, University of Kurdistan, Sanandaj, Iran.
چکیده [English]

Objective
In late 2019, the world faced a profound challenge with the emergence of the COVID-19 crisis, which had a lasting impact on economies across both developed and developing nations. The consequential impact reverberated through international financial markets, forcing their constriction and eventual closure as nations enforced sweeping nationwide quarantines. Simultaneously, healthcare expenditure soared, juxtaposed against a downturn in economic growth. Amid this upheaval, the domain of digital currencies, notably Bitcoin, experienced reverberations from the COVID-19 outbreak. Bitcoin's introduction signaled a new era of direct electronic payments and streamlined cross-border wealth transference, pivotal components underpinning the scaffolding of global trade. While COVID-19 doesn't solely account for the surge in Bitcoin prices, its presence likely played a substantial role, exacerbated by escalated uncertainties and risks amidst the global pandemic. The focal point of this study lies in examining the interplay between COVID-19 dynamics and the US dollar index on Bitcoin prices, utilizing Continuous Wavelet Transform (CWT) data spanning from April 8, 2020, to April 8, 2023. This study's novelty lies in its utilization of the Continuous Wavelet Transform, offering a distinctive edge within the realm of research on this subject.
 
Methods
The COVID-19 pandemic emerged as one of humanity's most daunting challenges in recent decades, significantly impacting digital currencies, epitomized by Bitcoin, as an indispensable economic sector. Primarily, this study aims to examine the complex effects of the COVID-19 pandemic and the US dollar index on Bitcoin prices over 977 days from April 2020 to April 2023, utilizing the Continuous Wavelet Transform (CWT). The research framework integrates two pivotal variables: the volume of confirmed COVID-19 cases per million and the tally of confirmed COVID-19 deaths per million.
 
Results
The findings unravel a compelling correlation between the frequency of COVID-19 cases and associated fatalities with Bitcoin price fluctuations during the study's duration. Intriguingly, the impact of case occurrences seemingly eclipses that of mortalities, possibly rooted in escalated uncertainties and risks during the pandemic, igniting an amplified demand surge for Bitcoin as investors sought refuge to safeguard their wealth and assets. Conversely, the US dollar index emerges as a noteworthy antagonist, wielding a pronounced negative influence on Bitcoin prices throughout the study period, potentially attributed to the plausible substitution of two commodities functioning as currency.
 
Conclusion
The study's findings reveal a clear positive impact of COVID-19 cases and deaths per million on Bitcoin prices during the observed period. This increase is largely driven by heightened demand, as investors, faced with risk and uncertainty, sought out Bitcoin as a safe-haven asset. On the flip side, the U.S. Dollar Index, acting as a competing asset, showed a significant negative effect on Bitcoin’s price during the same time. This is likely due to a substitution effect: as the U.S. dollar strengthens, Bitcoin prices tend to decline.

کلیدواژه‌ها [English]

  • COVID-19 Pandemic
  • Bitcoin
  • U.S. dollar index
  • Continuous wavelet transform
حیدری اشترینانی، سروش؛ خوچیانی، رامین و خرسند زاک، محمد (1399). تحلیل هم حرکتی بیت‌کوین، طلا و نرخ دلار با رویکرد هم‌دوستی و تحلیل موجک. فصلنامه سیاست‌های مالی و اقتصادی، 8(32)، 103-132.‎
رضازاده، علی؛ جهانگیری، شهاب؛ فهیدآذر، یعقوب و نیک‌پی پسیان، وحید (1401). تأثیر همه‌گیری کووید 19 بر رابطۀ بین بازار رمزارزها و شوک‌های قیمتی نفت (رویکرد خودرگرسیون با وقفه‌های توزیعی غیرخطی). نشریه مدیریت دارایی و تأمین مالی، 10(2)، 121-148.‎
سعیدی‌نژاد، سید رامین و لاله، سینا (1400). برآورد مدلی جهت پیش‌بینی روند ارزهای دیجیتال (بیت‌کوین، اتریوم) در دورة کرونا و پساکرونا با کمک سری زمانی. مهندسی مالی و مدیریت اوراق بهادار، 13(50). ‎
مصلی، مهسا؛ روحانی، آرمین و محمدی، مجید (1397). پول دیجیتال بیت‌کوین و بررسی نقش آن در تو سعه تجارت الکترونیک ایران. هفتمین کنفرانس ملی کاربردهای حسابداری و مدیریت، تهران، 807478.
هاتفی مجومرد، مجید؛ جلالی، ام‌البنین و رحیمی قاسم‌آبادی، محمد (1397). حباب‌های سفته‌بازی در بازار ارز دیجیتالی بیت‌کوین. دانش مالی تحلیل اوراق بهادار، 11(40)، 189-204.‎
یوسفی بهزاد فرخی، محمدعلی و قاسمی فر، ثمینه (1401). تحلیل رابطه نوسانات بیت‌کوین و نوسانات بورس اوراق بهادار تهران در خلال اپیدمی کروناویروس (رویکرد مارکف سویچینگ بیزین ور). راهبرد مدیریت مالی، 11(1)، 101-120.‎
 
References
 Amani, R., Ghaderi, S. & Ahmadzadeh, K. (2022). Covid-19 and Inflation Rate: An Evidence for OECD Countries. Iranian Journal of Economic Studies, 11(1), 85-102. doi: 10.22099/ijes.2023.43481.1825
Antoniadis, I., Sariannidis, N. & Kontsas, S. (2018). The effect of bitcoin prices on US dollar index price. In Advances in Time Series Data Methods in Applied Economic Research: International Conference on Applied Economics (ICOAE) 2018 (pp. 511-521). Springer International Publishing. https://doi.org/10.1007/978-3-030-02194-8_34
Apergis, E. & Apergis, N. (2020). Can the COVID-19 pandemic and oil prices drive the US Partisan Conflict Index? Energy Research Letters, 1(1), 13144.
Arouxet, M. B., Bariviera, A. F., Pastor, V. E. & Vampa, V. (2022). Covid-19 impact on cryptocurrencies: Evidence from a wavelet-based Hurst exponent. Physica A: Statistical Mechanics and its Applications, 596, 127170. https://doi.org/https://doi.org/10.1016/j.physa.2022.127170
Assaf, A., Bhandari, A., Charif, H. & Demir, E. (2022). Multivariate long memory structure in the cryptocurrency market: The impact of COVID-19. International Review of Financial Analysis, 82, 102132. https://doi.org/https://doi.org/10.1016/j.irfa.2022.102132
Baker, S. R., Bloom, N., Davis, S. J., Kost, K. J., Sammon, M. C. & Viratyosin, T. (2020). The unprecedented stock market impact of COVID-19 (No. w26945). National Bureau of economic research.
Belitski, M., Guenther, C., Kritikos, A. S. & Thurik, R. (2022). Economic effects of the COVID-19 pandemic on entrepreneurship and small businesses. Small Business Economics, 1-17. https://doi.org/10.1007/s11187-021-00544-y
Bouri, E., Molnar, P., Azzi, G., Roubaud, D., Hagfors, L.I. (2017). On the hedge and safe haven properties of Bitcoin: is it really more than a diversifier? Finance Research Letters. 20(1), 192–198.
Cao, G. & Xie, W. (2021). The impact of the shutdown policy on the asymmetric interdependence structure and risk transmission of cryptocurrency and China’s financial market. The North American Journal of Economics and Finance, 58, 101514. https://doi.org/https://doi.org/10.1016/j.najef.2021.101514
Catania, L., Grassi, S. & Ravazzolo, F. (2018). Forecasting cryptocurrencies financial time series. In CAMP Working Paper Series. Norwegian Business School. http://hdl.handle.net/11250/2489408
Cheema, M. A., Faff, R. & Szulczyk, K. R. (2022). The 2008 global financial crisis and COVID-19 pandemic: How safe are the safe haven assets? International Review of Financial Analysis83, 102316.
Chiu, J, (2018). The Economics of Cryptocurrencies– Bitcoin and Beyond, Financial Review, 53 (2), 217-229.
Chkili, W., Rejeb, A. B. & Arfaoui, M. (2021). Does bitcoin provide hedge to Islamic stock markets for pre-and during COVID-19 outbreak? A comparative analysis with gold. Resources Policy, 74, 102407.
Conlon, T. & McGee, R. (2020). Safe haven or risky hazard? Bitcoin during the COVID-19 bear market. Finance Research Letters, 35, 101607.
Conlon, T., Corbet, S., McGee, R. J. (2020). Are cryptocurrencies a safe haven for equity mar- kets? an international perspective from the covid-19 pandemic. Research in International Business and Finance, 101248.
Corbet, S., Larkin, C. & Lucey, B. (2020). The contagion effects of the COVID-19 pandemic: Evidence from gold and cryptocurrencies. Finance Research Letters, 35, 101554. https://doi.org/10.1016/j.frl.2020.101554
Corbet, S., Meegan, A., Larkin, C., Lucey, B. & Yarayova, L. (2018). Exploring the dynamic relationships between cryptocurrencies and other financial assets. Economics Letters, 165, 28–34. https://doi.org/10.1016/j.econlet.2018.01.004
Das, D., Kannadhasan, M., Tiwari, A. K. & Al-Yahyaee, K. H. (2018). Has co-movement dynamics in emerging stock markets changed after global financial crisis? New evidence from wavelet analysis. Applied Economics Letters, 25(20), 1447-1453. https://doi.org/10.1080/13504851.2018.1430307
David, S. A., Inácio Jr, C. & Machado, J. (2020). The recovery of global stock markets indices after impacts due to pandemics. Research in International Business and Finance, 55, 101335.
Demir, E., Bilgin, M. H., Karabulut, G. & Doker, A. C. (2020). The relationship between cryptocurrencies and COVID-19 pandemic. Eurasian Economic Review, 10, 349-360.
Dyhrberg, A. H. (2016). Bitcoin, gold and the dollar–A GARCH volatility analysis. Finance research letters16, 85-92.
Elsayed, A. H., Gozgor, G. & Lau, C. K. M. (2021). Causality and dynamic spillovers among cryptocurrencies and currency markets. International Journal of Finance and Economics, 27(2), 2026-2040. https://doi.org/10.1002/ijfe.2257.
Gates, B. (2020). Responding to Covid-19 — A Once-in-a-Century Pandemic? New England Journal of Medicine, 382(18), 1677-1679. https://doi.org/10.1056/NEJMp2003762
Gençay, R., Gençay, R., Selcuk, F. & Whitcher, B. J. (2001). An Introduction to Wavelets and Other Filtering Methods in Finance and Economics. Elsevier. https://EconPapers.repec.org/RePEc:eee:monogr:9780122796708
Ghecham, M. A. (2022). The impact of COVID-19 on economic growth of countries: What role has income inequality in it? Economies, 10(7), 158. https://doi.org/10.3390/economies10070158
Gherghina, Ș. C., Armeanu, D. Ș. & Joldeș, C. C. (2020). Stock market reactions to COVID-19 pandemic outbreak: Quantitative evidence from ARDL bounds tests and granger causality analysis. International journal of environmental research and public health17(18), 6729.
Gil-Alana, L. A. & Monge, M. (2020). Crude oil prices and COVID-19: Persistence of the shock. Energy Research Letters, 1(1), 13200.
Goodell, J.W. & Goutte, S. (2021a). Co-movement of COVID-19 and Bitcoin: evidence from wavelet coherence analysis. Finance Research Letters, 38, 101625. https://doi.org/ 10.1016/j.frl.2020.101625.
Goodell, J.W. (2020). COVID-19 and finance: agendas for future research. Finance research letters. 35, 101512. https://doi.org/10.1016/j.frl.2020.101512
Gronwald, M. (2021). How explosive are cryptocurrency prices? Finance Research Letters, 38, 101603. https://doi.org/https://doi.org/10.1016/j.frl.2020.101603
Guo, X., Lu, F. & Wei, Y. (2021). Capture the contagion network of bitcoin–Evidence from pre and mid COVID-19. Research in International Business and Finance, 58, 101484.
Habibi, F. & Amani, R. (2022). The Impact of Geopolitical Risk, World Economic Policy Uncertainty on Tourism Demand: Evidence from Malaysia. Iranian Economic Review, 26(2), 477-488. https://doi.org/10.22059/ier.2022.88176
Hakim das Neves, R. (2020). Bitcoin pricing: impact of attractiveness variables. Financial Innovation, 6(1), 21.‏ https://doi.org/10.1186/s40854-020-00176-3
Hatefi Majoomard, M., Jalali, O. & Rahimi Ghasemabadi, M. (2019). Speculative Bubbles in the Bitcoin Digital Currency Market. Financial Knowledge of Securities Analysis, 11(40), 189-204. (in Persian)
Heidari Ashtrinani, S., Khochiani, R. & Khorsand Zak, M. (2021). Analyzing the co-motion of bitcoin, gold and dollar with a wavy approach. Quarterly Journal of Fiscal and Economic Policies, 8 (32), 103-132. http://qjfep.ir/article-1-1179-fa.html (in Persian
Jareño, F., González, M. D. L. O., López, R. & Ramos, A. R. (2021). Cryptocurrencies and oil price shocks: A NARDL analysis in the COVID-19 pandemic. Resources Policy, 74, 102281. https://doi.org/10.1016/j.resourpol.2021.102281
Ji, Q., Bouri, E., Lau, C. K. M. & Roubaud, D. (2019). Dynamic connectedness and integration in cryptocurrency markets. International Review of Financial Analysis, 63, 257–272.
Ji, Q., Zhang, D. & Zhao, Y. (2020). Searching for safe-haven assets during the COVID-19 pandemic. International Review of Financial Analysis, 71, 101526. https://doi.org/https://doi.org/10.1016/j.irfa.2020.101526
Jiang, Y., Nie, H. & Monginsidi, J. Y. (2017). Co-movement of ASEAN stock markets: New evidence from wavelet and VMD-based copula tests. Economic Modelling, 64(C), 384-398. https://EconPapers.repec.org/RePEc:eee:ecmode:v:64:y:2017:i:c:p:384-398
Kristoufek, L. (2015). What are the main drivers of the Bitcoin price? Evidence from wavelet coherence analysis. PLoS One 10(4): e0123923. doi: 10.1371/journal.pone.0123923.
Kumar, M., Prashar, S. & Jana, R. (2019). Does international tourism spur international trade and output? Evidence from wavelet analysis. Tourism Economics, 25(1), 22-33. https://doi.org/10.1177/1354816618788392
Lahmiri, S. & Bekiros, S. (2020). The impact of COVID-19 pandemic upon stability and sequential irregularity of equity and cryptocurrency markets. Chaos, solitons, and fractals, 138, 109936. https://doi.org/10.1016/j.chaos.2020.109936
Li, X. & Wang, C. A. (2017). The technology and economic determinants of cryptocurrency exchange rates: The case of Bitcoin. Decision support systems, 95, 49-60. https://doi.org/10.1016/j.dss.2016.12.001
Lien, D., Hung, P. H. & Pan, C. T. (2020). Price Limit Changes, Order Decisions, and StockPrice Movements: An Empirical Analysis of the Taiwan Stock Exchange. Review of Quantitative Finance and Accounting, 55(1), 239–268. https://doi.org/10.1007/s11156- 019-00842-3
Maesa, D., Marino, A. & Ricci, L. (2019). The bow tie structure of the Bitcoin users graph. Applied Network Science, 4(1), 56-69.
Mariana, C. D., Ekaputra, I. A., & Husodo, Z. A. (2021). Are Bitcoin and Ethereum safe-havens for stocks during the COVID-19 pandemic? Finance research letters38, 101798. https://doi.org/10.1016/j.frl.2020.101798
Mohsin, A., Hongzhen, L. & Hossain, S. F. (2021). Impact of COVID-19 pandemic on consumer economy: Countermeasures analysis. SAGE Open, 11(2), 1-10. http://doi.org/10.1177/21582440211008875
Mosli, M., Rouhani, A. & Mohammadi, M. (2017). Bitcoin digital money and the study of its role in the development of e-commerce in Iran. The 7th National Conference on Accounting and Management Applications, https://civilica.com/doc/807478 (in Persian)
Narayan, A., Cojocaru, A., Agrawal, S., Bundervoet, T., Davalos, M. E., Garcia, N., ... & Yonzan, N. (2022). COVID-19 and economic inequality: Short-term impacts with long-term consequences (No. 9902). The World Bank.
Narayan, P. K., Narayan, S., Rahman, R. E. & Setiawan, I. (2019). Bitcoin price growth and Indonesia's monetary system. Emerging Markets Review, 38, 364-376.
Oad Rajput, S. K., Soomro, I. A. & Soomro, N. A. (2022). Bitcoin Sentiment Index, Bitcoin Performance and US Dollar Exchange Rate. Journal of Behavioral Finance, 23(2), 150-165. https://doi.org/10.1080/15427560.2020.1864735
Popper, N. (2015). Digital gold: The untold story of Bitcoin. Penguin UK.
Qin, M., Su, C. W. & Tao, R. (2021). BitCoin: A new basket for eggs? Economic Modelling, 94, 896-907. https://doi.org/10.1016/j.econmod.2020.02.031
Reza Zadeh, A., Jahangiri, S., Fahid Azer, Y. & Nikpey Pesyan, V. (2022). Investigating the Impact of Covid-19 on the Relationship between Cryptocurrencies and Oil Price Shocks Using the Non-Linear Autoregressive Distributed Lag (NARDL) Approach. Journal of Asset Management and Financing, 10(2), 121-148. doi: 10.22108/amf.2022.134421.1750. (in Persian)
Saeedi nezhad, S. R. & Laleh, S. (2022). Estimation of a model for predicting the trend of digital currencies (Bitcoin, Ethereum) in the corona and post-corona periods with the help of time series. Financial Engineering and Portfolio Management, 13(50), 195-209.
(in Persian).
Salisu, A. A., Ebuh, G. U. & Usman, N. (2020). Revisiting oil-stock nexus during COVID-19 pandemic: Some preliminary results. International Review of Economics & Finance, 69, 280-294. https://doi.org/10.1016/j.iref.2020.06.023
Sarkodie, S. A., Ahmed, M. Y. & Owusu, P. A. (2022). COVID-19 pandemic improves market signals of cryptocurrencies–evidence from Bitcoin, Bitcoin Cash, Ethereum, and Litecoin. Finance Research Letters, 44, 102049. https://doi.org/10.1016/j.frl.2021.102049
Seetharaman, A., Saravanan, A. S., Patwa, N. & Mehta, J. (2017). Impact of Bitcoin as a world currency. Accounting and Finance Research, 6(2), 230-246.
Segal, S. & Gerstel, D. (2020). The global economic impacts of COVID-19. SIS—Center for Strategic & International Studies. Retrieved from https://www.csis.org/analysis/global-economicimpacts- covid-19.
Selmi, R., Mensi, W., Hammoudeh, S. & Bouoiyour, J. (2018). Is bitcoin a hedge, a safe haven or a diversifier for oil price movements? A comparison with Gold. Energy Economics, 74, 787–801. https://doi.org/10.1016/j.eneco.2018.07.007
Shahzad, S. J. H., Bouri, E., Roubaud, D., Kristoufek, L. & Lucey, B. (2019). Is bitcoin a better safe-haven investment than gold and commodities? International Review of Financial Analysis, 63, 322-330.
Shi, Y., Tiwari, A. K., Gozgor, G. & Lu, Z. (2020). Correlations among cryptocurrencies: Evidence from multivariate factor stochastic volatility model. Research in International Business and Finance, 53, 101231.
Silva, P. C., Batista, P. V., Lima, H. S., Alves, M. A., Guimarães, F. G., & Silva, R. C. (2020). COVID-ABS: An agent-based model of COVID-19 epidemic to simulate health and economic effects of social distancing interventions. Chaos, Solitons & Fractals139, 110088. Smales, L. A. (2019). Bitcoin as a safe haven: Is it even worth considering? Finance Research Letters, 30, 385-393.
Sun, X., Lu, X., Yue, G. & Li, J. (2016). Cross-Correlations Between the US Monetary Policy, US Dollar Index and Crude Oil Market. Physica A, 467, 326–344. https://doi.org/10.1016/j.physa.2016.10.029
Tiwari, A. K., Das, D. & Dutta, A. (2019). Geopolitical risk, economic policy uncertainty and tourist arrivals: Evidence from a developing country. Tourism Management, 75, 323-327. https://doi.org/https://doi.org/10.1016/j.tourman.2019.06.002
Torrence, C. & Compo, G.P. (1998). A Practical Guide to Wavelet Analysis. Bulletin of the American Meteorological Society, 79, 61-78.
https://doi.org/10.1175/1520-0477(1998)079<0061:APGTWA>2.0.CO;2
Urquhart, A. & Zhang, H. (2019). Is Bitcoin a hedge or safe haven for currencies? An intraday analysis. International Review of Financial Analysis, 63, 49-57. https://doi.org/10.1016/j.irfa.2019.02.009
Wang, X., Chen, X. & Zhao, P. (2020). The relationship between Bitcoin and stock market. International Journal of Operations Research and Information Systems (IJORIS), 11(2), 22-35.
Wang, X., Wang, L., Zhang, X. & Fan, F. (2022). The spatiotemporal evolution of COVID-19 in China and its impact on urban economic resilience. China Economic Review, 74, 101806. https://doi.org/10.1016/j.chieco.2022.101806
Wen, F., Tong, X. & Ren, X. (2022). Gold or Bitcoin, which is the safe haven during the COVID-19 pandemic? International Review of Financial Analysis, 81, 102121.
Williamson, A. E., Tydeman, F., Miners, A., Pyper, K. & Martineau, A. R. (2022). Short-term and long-term impacts of COVID-19 on economic vulnerability: a population-based longitudinal study (COVIDENCE UK). BMJ open, 12(8), e065083. http://dx.doi.org/10.1136/bmjopen-2022-065083
Wu, C. C., Ho, S. L. & Wu, C. C. (2022). The determinants of Bitcoin returns and volatility: Perspectives on global and national economic policy uncertainty. Finance Research Letters, 45, 102175. https://doi.org/10.1016/j.frl.2021.102175
Yousefi Behzad Farokhi, M. A. & Qasemifar, S. (2023). Analysis of the Relationship between Bitcoin Fluctuations and Tehran Stock Exchange Fluctuations During the Coronavirus Epidemic (Markov Switching Baysian VAR). Financial Management Strategy, 11(1), 101-120. doi: 10.22051/jfm.2023.40085.2675. (in Persian)