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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">JDS</journal-id>
<journal-title-group><journal-title>Journal of Data Science</journal-title></journal-title-group>
<issn pub-type="epub">1683-8602</issn><issn pub-type="ppub">1680-743X</issn><issn-l>1680-743X</issn-l>
<publisher>
<publisher-name>School of Statistics, Renmin University of China</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">JDS1187</article-id>
<article-id pub-id-type="doi">10.6339/25-JDS1187</article-id>
<article-categories><subj-group subj-group-type="heading">
<subject>Data Science in Action</subject></subj-group></article-categories>
<title-group>
<article-title>Interval Forecasting in Time Series Analysis: Application to COVID-19 and Beyond</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-9277-4243</contrib-id>
<name><surname>Shao</surname><given-names>Q.</given-names></name><email xlink:href="mailto:qin.shao@utoledo.edu">qin.shao@utoledo.edu</email><xref ref-type="aff" rid="j_jds1187_aff_001">1</xref><xref ref-type="fn" rid="cor1">∗</xref>
</contrib>
<aff id="j_jds1187_aff_001"><label>1</label>Department of Mathematics and Statistics, Department of Population Health, <institution>The University of Toledo</institution>, Toledo, OH 43606, <country>USA</country></aff>
</contrib-group>
<author-notes>
<corresp id="cor1"><label>∗</label>Email: <ext-link ext-link-type="uri" xlink:href="mailto:qin.shao@utoledo.edu">qin.shao@utoledo.edu</ext-link>.</corresp>
</author-notes>
<pub-date pub-type="ppub"><year>2025</year></pub-date><pub-date pub-type="epub"><day>9</day><month>5</month><year>2025</year></pub-date><volume>23</volume><issue>4</issue><fpage>659</fpage><lpage>675</lpage><history><date date-type="received"><day>1</day><month>10</month><year>2024</year></date><date date-type="accepted"><day>15</day><month>4</month><year>2025</year></date></history>
<permissions><copyright-statement>2025 The Author(s). Published by the School of Statistics and the Center for Applied Statistics, Renmin University of China.</copyright-statement><copyright-year>2025</copyright-year>
<license license-type="open-access" xlink:href="https://creativecommons.org/licenses/by/4.0/">
<license-p>Open access article under the <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by/4.0/">CC BY</ext-link> license.</license-p></license></permissions>
<abstract>
<p>Forecasting is essential for optimizing resource allocation, particularly during crises such as the unprecedented COVID-19 pandemic. This paper focuses on developing an algorithm for generating <italic>k</italic>-step-ahead interval forecasts for autoregressive time series. Unlike conventional methods that assume a fixed distribution, our approach utilizes kernel distribution estimation to accommodate the unknown distribution of prediction errors. This flexibility is crucial in real-world data, where deviations from normality are common, and neglecting these deviations can result in inaccurate predictions and unreliable confidence intervals. We evaluate the performance of our method through simulation studies on various autoregressive time series models. The results show that the proposed approach performs robustly, even with small sample sizes, as low as 50 observations. Moreover, our method outperforms traditional linear model-based prediction intervals and those derived from the empirical distribution function, particularly when the underlying data distribution is non-normal. This highlights the algorithm’s flexibility and accuracy for interval forecasting in non-Gaussian contexts. We also apply the method to log-transformed weekly COVID-19 case counts from lower-middle-income countries, covering the period from June 1, 2020, to March 13, 2022.</p>
</abstract>
<kwd-group>
<label>Keywords</label>
<kwd>autoregressive time series</kwd>
<kwd>empirical cumulative distribution function</kwd>
<kwd>kernel density estimation</kwd>
<kwd>prediction interval</kwd>
</kwd-group>
</article-meta>
</front>
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