linearity在assumptions of linear regression中怎么理解?

老师，这里要缩小bid-ask spread, 只降低ask，而bid保持不变的情况下也能使spread缩小呀，为什么要同时做到降低bid, ask才能使spread缩小呢？

请详细讲解一下这道题，尤其说明交互相如何计算，谢谢！

t statistic 要大于critical value这个coefficient 才有效吗？我们学的时候好像没有这个说法，multiple linear regression和time series analysis 不都是直接拿来用的吗

第三题为啥C不对

Q4，我记得课程中不是有一段说，资本深化边际效用会递减么，那现在投资不应该投一个资本作用更大的国家，所以资本深化这项不应该是最不能支持的选项么？

这边应该是说管理层故意将Mscore做低吧，而不是讲师说的做高吧？

mock1中，the client's portfolio contains a bond with a par value of 10 million Bahraini dinar (BHD) and an annual interest rate of 5%, paid semi-annually. Based on current market conditions, Hassan would like to increase the client's equity exposure, but prefers not to sell this bond. Ahmed suggests establishing an equity swap that would allow the client to increase equity exposure without selling the bond. Hassan sets up an equity return for fixed payment equity swap for the client with a BHD 10 million notional value and semi-annual payments. The first semi-annual period after setting up the equity swap, the underlying unannualized equity performance was –2.3% and the present value of all remaining fixed cash flows after this first payment are equal to BHD 11,187,500. 求The fair value (in BHD) of the equity swap immediately after the first semi-annual payment is closest to:–1,417,500. 能解释一下为什么这么计算么

mock1里，这道题为什么是用第三种情况，公司剩余收益逐年降为平均水平的公式来计算的？题目中没有具体提到这一点。问题是：Based on the information given, Parker should conclude that Company D’s share is: overvalued

老师，这个例题C，老师说有3000是按10.05成交了，另外2000是按更低价成交，因此平均价格是10.01。说是低于9.95。讲walk down又说高于9.95的都可以成交。剩余2000股