求翻译：但该模型在应用中存在以下问题：违约率直接取自历史数据平均值，但实证研究表明，违约率与宏观经济状况有直接关系，并非固定不变，假定资产收益服从正态分布，但实证研究表明实际分布多呈现厚尾特征；关于企业资产收益之间的相关度等于公司证券收益之间的相关度的假设有待验证方法计算结果对于这一假定的敏感性很高。是什么意思？

However, the model in the application of the following problems: the default rates directly from the average of the historical data, but empirical studies show that default rates and macroeconomic conditions have a direct relationship is not fixed, assume that asset returns follow a normal distribut

However, this model is in the application of the following: default rate directly from historical data, but average empirical studies indicate that default rates and macro-economic situation, there is a direct relationship is not fixed, it is assumed that income from assets subject to normal distrib

But this model has following problem in the application: Breaks a contract the straightforward acceptance from the historical data mean value, but the real diagnosis research indicated, the violation rate has the direct relations with the macroscopic financial circumstance, by no means fixed invaria

But the model in application in the exists following problem: default rate directly from history data average, but empirical research indicates that, default rate and macroeconomic status has directly relationship, is not fixed does not variable, assumes that assets income obedience normal distribut

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