差別利率 - 經濟

: 推 McGyver:所以我的下一個疑問是 規定開始要採用差別利率 會不會其實 04/06 13:11
: → McGyver:效果還是一樣？ 還是只有那些高風險的人去借而已？ 04/06 13:11

I think.. you are a student
you are asking a question which is not a question
In the real world, there are not economic theories everywhere.
And never try to put all phenomena into economic theories

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The key risk factor is transformation.
Transform "application form" into "score card"
Transform "score card" into "interest rate spread"

If you have run any econometric model,
you would find that adjuested R square running up to 60% or 70%
already have powerful explanatory ability.

Suppose the adjusted R squre represtnts the forecasting
accuracy of bad debt ratio and we have a adjusted R square of 75%.
And the accurate bad debt ratio is 15%.
Therefore you forecast the bad debt ratio is 11.25%
How much margin spread should you charge if
the current (saving) interest rate is 1%
the recovery rate is 0%, and there is no friction cost?

1+1%=(1+R)(1-15%) ---> R=18%
1+1%=(1+r)(1-11.25%)---> r=13.8%

The adverse selection exists because banks cannot
identify who is the lemon; therefore banks face only
downside risk and cannot enjoy upside benefit.

It's no surprise banks suffer from low forecasting accuracy.
How can you judge the credit of the debtor only by a paper?
But it should be the destiny of the cash card (and credit card)
Card card features its convenience and simplicity.
If banks want to increas its forecasting accuracy
of bad debt ratio and adopt different spread levels,
they would enhance the credit investigation process.
But if banks ehance the process, it is not cash card any more.

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The key is not adverse selection.
Banks cannot forecast the bad debt ratio well now.
How can they adopt different spread levels?
So..forget the spread levels. It's only an unreachable gift.


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