## 4 Analysis and Results  
Before the empirical analysis, we examined the correlation between variables to address the concern of multicollinearity. The results are reported in Table 3.  
The correlation coefficient matrix shows that most correlation coefficients are less than 0.5; thus, there is no severe multicollinearity problem. The estimates of Equation (2) are reported in Table 4.  
As shown in Table 4, we estimate whether or not the straw effect exists after the operation of KTX, based on a panel data model. Columns (1)-(5) report the change in relative attraction of Seoul, Busan, Daegu, Gwangju, and Deajon before and after the operation of KTX. All regressions include city and time-fixed effects. We found that the coefficient of _kkx1_ was significantly positive in the situation of \begin{table}
\begin{tabular}{c c c c c c} \hline  & **(1)** & **(2)** & **(3)** & **(4)** & **(5)** \\ \hline
**Models** & **Model 1** & **Model 2** & **Model 3** & **Model 4** & **Model 5** \\ \hline ktx1 & 0.2487 \({}^{*}\) & 0.0051 & \(-\)0.0927 & \(-\)0.0544 & 0.1724 \\  & (0.0914) & (0.0979) & (0.2408) & (0.5041) & (0.0782) \\ Inecoppr & \(-\)3.3319 & \(-\)2.1424 & 1.5325 & 0.1495 & 0.2227 \\  & (2.7746) & (2.1886) & (2.1513) & (1.5743) & (1.5489) \\  & 79.5926 \({}^{***}\) & \(-\)19.5364 & \(-\)105.1740 & 16.7092 & 79.8439 \({}^{**}\) \\  & (8.4704) & (20.4470) & (57.2592) & (24.3095) & (18.1215) \\ Inuniver & \(-\)0.3994 & 0.7043 & 1.4213 & \(-\)0.5460 & \(-\)1.1135 \\  & (1.0236) & (0.9877) & (1.1881) & (0.4407) & (1.1551) \\ Ingland & 0.4914 & 0.9390 & 0.1488 & \(-\)1.3867 & \(-\)0.3034 \({}^{**}\) \\  & (0.3697) & (0.4091) & (0.3500) & (0.7822) & (0.0677) \\  & \(-\)0.1161 & 0.0821 & \(-\)0.1019 & 0.7205 & 1.0843 \({}^{*}\) \\  & (0.4358) & (0.4213) & (0.6616) & (0.4893) & (0.4220) \\  & 1.7040 & \(-\)11.1162 & \(-\)0.3138 & \(-\)1.5278 & \(-\)3.3882 \\  & (0.9729) & (6.7491) & (0.9319) & (0.8912) & (12.2789) \\  & \(-\)0.5951 \({}^{**}\) & 0.2715 & 0.4862 & 0.8623 \({}^{**}\) & \(-\)0.0313 \\  & (0.1103) & (0.2129) & (0.2344) & (0.2340) & (0.1100) \\ Indtravel & \(-\)0.8399 & 46.1717 & 0.9922 & \(-\)0.7073 & \(-\)0.0375 \\  & (0.6030) & (32.1931) & (0.6256) & (0.4695) & (7.0598) \\ Constant & 12.4904 & \(-\)239.3733 & \(-\)9.9969 & 8.8060 & 11.0173 \\  & (9.9992) & (159.5139) & (13.7150) & (12.3647) & (9.9305) \\ Time control & Yes & Yes & Yes & Yes & Yes \\ City control & Yes & Yes & Yes & Yes & Yes \\ Observations & 68 & 68 & 68 & 68 & 68 \\ R\({}^{2}\) & 0.5091 & 0.5290 & 0.4514 & 0.5660 & 0.4334 \\ \hline \end{tabular}
\end{table} 
Table 3: Correlation coefficient matrix. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Variable:** & **RD** & **ktx1** & **Lnceoppor** & **Enterm** & **Lnuniver** & **Lngland** & **Lnteachp** & **Lncpi** & **Lnbed** & **Lndtravel** \\ \hline RD & 1.00 & & & & & & & & \\ ktx1 & 0.01 & 1.00 & & & & & & & \\ Inecoppr & 0.14 & 0.52 & 1.00 & & & & & & \\ enterm & 0.27 & 0.16 & 0.29 & 1.00 & & & & & \\ Inuniver & 0.21 & 0.15 & 0.02 & 0.83 & 1.00 & & & & \\ Ingland & \(-\)0.42 & \(-\)0.13 & \(-\)0.49 & \(-\)0.68 & \(-\)0.46 & 1.00 & & & \\ Inteachp & 0.11 & 0.15 & 0.29 & 0.67 & 0.78 & \(-\)0.53 & 1.00 & & \\ Incpi & \(-\)0.02 & 0.57 & 0.65 & 0.26 & 0.20 & \(-\)0.13 & 0.34 & 1.00 & \\ Inbed & 0.04 & 0.37 & 0.76 & 0.34 & \(-\)0.08 & \(-\)0.51 & 0.24 & 0.43 & 1.00 & \\ Indtravel & 0.26 & 0.12 & 0.02 & 0.01 & 0.09 & 0.09 & \(-\)0.06 & 0.17 & \(-\)0.20 & 1.00 \\ \hline \end{tabular}
\end{table} 
Table 4: Baseline results. Seoul, which suggests that the relative attraction of Seoul increased after the operation of KTX, while this effect was not significant or even negative in terms of the other four cities.