<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Mixed Logit | Yichao Jin | Academic Blog</title><link>https://yichao2022.github.io/tags/mixed-logit/</link><atom:link href="https://yichao2022.github.io/tags/mixed-logit/index.xml" rel="self" type="application/rss+xml"/><description>Mixed Logit</description><generator>HugoBlox Kit (https://hugoblox.com)</generator><language>en-us</language><lastBuildDate>Tue, 24 Mar 2026 00:00:00 +0000</lastBuildDate><image><url>https://yichao2022.github.io/media/icon_hu_da05098ef60dc2e7.png</url><title>Mixed Logit</title><link>https://yichao2022.github.io/tags/mixed-logit/</link></image><item><title>Waiting Time as a Behavioral Barrier: Unmasking Procrastination in Vaccination</title><link>https://yichao2022.github.io/blog/vaccination-delays/</link><pubDate>Tue, 24 Mar 2026 00:00:00 +0000</pubDate><guid>https://yichao2022.github.io/blog/vaccination-delays/</guid><description>&lt;p&gt;In the realm of public health, we often focus on &lt;strong&gt;safety&lt;/strong&gt; and &lt;strong&gt;efficacy&lt;/strong&gt; as the primary drivers of vaccine uptake. However, our recent research reveals a hidden, yet potent structural barrier: &lt;strong&gt;Waiting Time&lt;/strong&gt;.&lt;/p&gt;
&lt;h2 id="the-cliff-of-procrastination"&gt;The &amp;ldquo;Cliff&amp;rdquo; of Procrastination&lt;/h2&gt;
&lt;p&gt;Are humans rational &amp;ldquo;exponential discounters,&amp;rdquo; or are we impulsive &amp;ldquo;hyperbolic discounters&amp;rdquo;?&lt;/p&gt;
&lt;p&gt;Using a &lt;strong&gt;Mixed Logit&lt;/strong&gt; model, we analyzed the decision-making process behind vaccination timing. The results were striking. Instead of a gradual decline in utility over time, we found what can only be described as a &amp;ldquo;behavioral cliff.&amp;rdquo;&lt;/p&gt;
&lt;p&gt;If you ask someone to wait 3 months for a vaccine, their willingness to get vaccinated doesn&amp;rsquo;t just dip—it drops significantly. This validates the presence of &lt;strong&gt;Present Bias&lt;/strong&gt; ($\kappa = 1.056$).&lt;/p&gt;
&lt;h2 id="key-findings"&gt;Key Findings&lt;/h2&gt;
&lt;ol&gt;
&lt;li&gt;&lt;strong&gt;Discounting is Non-Linear&lt;/strong&gt;: The perceived disutility of a 3-month delay is comparable to a substantial reduction in the vaccine&amp;rsquo;s clinical efficacy.&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Institutional Trust Matters&lt;/strong&gt;: Individuals with lower trust in institutions exhibit significantly higher sensitivity to service delays. For them, waiting isn&amp;rsquo;t just an inconvenience; it&amp;rsquo;s a psychological burden.&lt;/li&gt;
&lt;li&gt;&lt;strong&gt;Vulnerability Heterogeneity&lt;/strong&gt;: Older populations and those with higher health concerns surprisingly show different delay-sensitivity patterns, often linked to their perceived &amp;ldquo;escape&amp;rdquo; from risk.&lt;/li&gt;
&lt;/ol&gt;
&lt;h2 id="policy-implications-time-to-protection"&gt;Policy Implications: &amp;ldquo;Time-to-Protection&amp;rdquo;&lt;/h2&gt;
&lt;p&gt;The takeaway for policymakers is clear: &lt;strong&gt;Time is a metric of performance.&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;To increase uptake, we must minimize the &amp;ldquo;time-to-protection&amp;rdquo; as much as we maximize clinical results. Vaccination campaigns should be as much about logistics and immediate accessibility as they are about science communication.&lt;/p&gt;
&lt;hr&gt;
&lt;p&gt;&lt;em&gt;This post is based on my Job Market Paper (JMP) and upcoming PhD dissertation defense. Stay tuned for more insights as I prepare for my Final Oral Examination on April 14, 2026.&lt;/em&gt;&lt;/p&gt;</description></item></channel></rss>