翻译如下：拟合模型时出现错误。任一初始参数值的参数约束是坏的。这个错误可发生，例如，如果您要求最大似然解，并同时指定阻止总体协方差矩阵形式为正定的初始参数值。检查以确保每个内生变量都有一个与其相关的残差变量（错误变量）。
SSTs are a combination of technology and self-service that can be defined as technological interfaces that allow customers to produce a service without being dependent on direct service employee involvement (Lee and Lyu, 2016; Meuter et al., 2000). Amongst the various types of SSTs, the introdu...
And even if the Fed is cautious and sober-minded, are we sure that central bankers can value these assets more accurately than private investors? If the Fed were to blow through the rest of its current stock of Treasuries, it would have invested more than $2500 for every man, woman, ...