你好，这个是百题里第9题 看了答案 对这个解题有疑问 题目应该是说到，分别是2006.1.15.和2007.1.15，各买进一个股票，2008.1.15两只股票全部卖掉，那这里算时间加权回报，答案里说按照一只股票，分两年内各自回报再求几何平均，但是这个94应该是另外买的一只股票价格，又不是第一只滚到一年后的价格，还有也有两只股票，是一个组合 怎么这里就算一个呢?

omit variables 导致SE和参数标准差变大还是变小？ 谢谢！

According to the following statements about auto loan Receivable-backed securities, which statement is not correct? A A subprime loan is one granted to borrowers with higher credit quality. B The purpose of a reserve account is to provide internal credit enhancement C Overcollateralization means that the aggregate principle balance of the automobile loan contracts exceeds the principle balance of the notes. 这题c也不对吧，怎么能说贷款本金大于note的就是过度抵押呢？应该说是抵押物value大于note才对吧，a的话如果有比他层级更低的话他就是比较好的吧

调整R2不是等于R2分子分母分别除以自由度么，那分子分母都是大于等于0的，自由度也不可能为负，为啥调整R2会小于0呢

这里从经济学意义讲的调整R2一般小于R2的原因听得有些模糊，请老师再解释下

According to the following statements, which statement is correct? A CMBS are securities backed by a pool of commercial mortgage loans on capital-gain-producing property. B The characteristic of call protection of CMBS makes CMBS to trade in the market more like corporate bonds than RMBS. C The call protection of CMBS has two forms: at the structure level and at the loan level. a和c为什么不对？

这里计算调整后的R2直接分子用RSS除以K不是很简便么？为啥要用1减去这一长串

这里的exact 线性关系的判断标准是啥？如果有X1和X2之间有线性关系的话，岂不是会产生多重共线性么

为什么不是A (16.2-15)/15=0.08 e0.08-1不是这个思路，这道题怎么解？

一般不是计息次数越多，收益越高吗。为什么这里计息两次和计息四次的收益一样呢