Non-fungible tokens (NFTs) are one-of-a-kind digital assets that are stored on a blockchain. Examples of NFTs include art (e.g., image, video, animation), collectables (e.g., autographs), and objects from games (e.g., weapons and poisons). NFTs provide content creators and artists a way to promote and sell their unique digital material online. NFT coins underpin the ecosystems that support NFTs and are a new and emerging asset class and, as a new and emerging asset class, NFT coins are not immune to economic uncertainty. This research seeks to address the following questions. What is the time and frequency relationship between economic uncertainty and NFT coins? Is the relationship similar across different NFT coins? As an emerging asset, do NFT coins exhibit explosive behavior and if so, what role does economic uncertainty play in their formation? Using a new Twitter-based economic uncertainty index and a related equity market uncertainty index it is found that wavelet coherence between NFT coin prices (ENJ, MANA, THETA, XTZ) and economic uncertainty or market uncertainty is strongest during the periods January 2020 to July 2020 and January 2022 to July 2022. Periods of high significance are centered around the 64-day scale. During periods of high coherence, economic and market uncertainty exhibit an out of phase relationship with NFT coin prices. Network connectedness shows that the highest connectedness occurred during 2020 and 2022 which is consistent with the findings from wavelet analysis. Infectious disease outbreaks (COVID-19), NFT coin price volatility, and Twitter-based economic uncertainty determine bubbles in NFT coin prices.

中文翻译：

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NFT 币与经济不确定性之间的时间和频率动态

不可替代代币（NFT）是存储在区块链上的独一无二的数字资产。NFT 的例子包括艺术品（例如图像、视频、动画）、收藏品（例如亲笔签名）和游戏中的物品（例如武器和毒药）。NFT 为内容创作者和艺术家提供了一种在线推广和销售其独特数字材料的方式。NFT 币支撑着支持 NFT 的生态系统，是一种新兴的资产类别，而且作为一种新兴的资产类别，NFT 币也不能免受经济不确定性的影响。本研究旨在解决以下问题。经济不确定性与NFT币之间的时间频率关系是怎样的？不同 NFT 币之间的关系是否相似？作为一种新兴资产，NFT 币是否表现出爆炸性行为？如果是，经济不确定性在其形成过程中扮演什么角色？使用基于 Twitter 的新经济不确定性指数和相关的股市不确定性指数发现，NFT 代币价格（ENJ、MANA、THETA、XTZ）与经济不确定性或市场不确定性之间的小波相关性在 2020 年 1 月至 7 月期间最强2020 年和 2022 年 1 月至 2022 年 7 月。重要时期以 64 天为中心。在高度一致性时期，经济和市场的不确定性与 NFT 币价格呈现出反相关系。网络连通度显示，连通度最高发生在 2020 年和 2022 年，这与小波分析的结果一致。传染病爆发（COVID-19）、NFT币价格波动以及基于Twitter的经济不确定性决定了NFT币价格的泡沫。