\begin{table}[htbp]
\centering
\caption{Descriptive statistics.}
\label{table_2}
\begin{tabular}{llllll}
S/N & Variable & Mean & Standard deviation & Minimum & Maximum \\
1 & Number of non-native Ph. D students in Zhejiang who come from provinces where they earned their Master’s Degrees & 17.954 & 21.671 & 0 & 121 \\
2 & Number of non-native Ph. D students in Zhejiang who come from provinces where they were born & 23.107 & 28.085 & 0 & 158 \\
3 & Surname distance & 0.310 & 0.100 & 0.082 & 0.564 \\
4 & Geographic distance (km) & 1516.793 & 782.466 & 178 & 3928 \\
\end{tabular}
\end{table}

\begin{table}[htbp]
\centering
\caption{Correlation coefficients matrix.}
\label{table_3}
\begin{tabular}{llllll}
S/N & Variable & 1 & 2 & 3 & 4 \\
1 & Number of non-native Ph. D students in Zhejiang who come from provinces where they earned their Master’s Degrees & 1.000 &  &  &  \\
2 & Number of non-native Ph. D students in Zhejiang who come from provinces where they were born & 0.979 & 1.000 &  &  \\
3 & Surname distance & -0.197 & -0.194 & 1.000 &  \\
4 & Geographic distance (km) & -0.453 & -0.422 & 0.325 & 1.000 \\
\end{tabular}
\end{table}

\begin{table}[htbp]
\centering
\caption{Empirical estimation results (dependent variable: logarithm of the number of Ph.D. students in Zhejiang who come from provinces where they earned their Master’s Degrees).}
\label{table_4}
\begin{tabular}{lllll}
Variable & 1 & 2 & 3 & 4 \\
Surname distance & -1.199(0.795) & -4.331*** (1.542) & -1.209(2.740) &  \\
Ln (Geographic distance) & 0.673*** (0.117) & -0.673*** (0.110) & -0.961*** (0.258) &  \\
Ln (Surname distance $\times$ Geographic distance) &  &  &  & -1.272*** (0.242) \\
Time Treds & 0.107*** (0.026) & 0.138* (0.079) & 0.100(0.258) & 0.392** (0.184) \\
Time Treds $\times$ Surname distance &  & 1.881*** (0.408) & -1.100(1.243) & 3.084*** (0.940) \\
Time Treds$^2$ $\times$ Surname distance &  & -0.198*** (0.033) & 0.098(0.121) & -0.261*** (0.100) \\
Ln (Time Treds $\times$ Geographic distance) &  &  & 0.146** (0.069) & 0.079** (0.034) \\
Ln (Time Treds$^2$ $\times$ Geographic distance) &  &  & -0.014** (0.006) & 0.020(0.005) \\
Constant & 6.928*** (0.747) & 0.677*** (0.794) & 6.962*** (1.489) & 3.380*** (0.578) \\
Observations & 252 & 252 & 252 & 252 \\
$R^2$ & 0.245 & 0.342 & 0.359 & 0.380 \\
\end{tabular}

Standard errors in parentheses, ** p$<$0.05, *** p$<$0.01.
\end{table}

(2) in Table~\ref{tab:table_4} as an example. The estimated coefficients for surname distance and geographic distance are respectively -4.331 and -0.673 which are both significant. This revealed that students who pursue their higher education here in China are not only influenced by geographic distance but also by the cultural difference. As for the latter, the wider the cultural difference between provinces, the fewer the interprovincial students. Secondly, Table~\ref{tab:table_4} also shows that the impact of surname distance has been decreasing when compared with time factor. A similar result is seen in Table 5 as well, in which the impact of surname distance is even more obvious. The empirical study showed that the smaller the surname distance, the higher the cultural affinity between provinces and the more inclined students are to study across provincial borders. According to \cite{Du_1991, Lou_2012}, since Chinese people are mostly named after their fathers instead of their mothers, their surnames are quite genetically informative in the family. If the naming rule remains unchanged, individuals bearing the same surname will share the same Y chromosome on the base pairs; similar surname frequency between two groups of people is echoed in the genetic distribution. Interprovincial study in China might be a reflection of being gregarious of the same surnamed people.

\section{Conclusion}

This paper discusses interprovincial study in China by taking non-native Ph. D students in Zhejiang Province as an example. The discussion uses surname distance as the proxy variable for cultural distance and has got the following findings: the larger the surname distance between the provinces, the wider the cultural distance and the wider the cultural difference, the more negative the impact on students’ decision whether to seek their Ph. D education in another province. What should be pointed out is that the