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Beta calculation is incorrect in Lecture 30? #278

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jcrmatos opened this issue Aug 27, 2018 · 1 comment
Open

Beta calculation is incorrect in Lecture 30? #278

jcrmatos opened this issue Aug 27, 2018 · 1 comment

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@jcrmatos
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Hello,

In lecture 30 ( (The Capital Asset Pricing Model and Arbitrage Pricing Theory) Beta was calculated with
AAPL_results = regression.linear_model.OLS(R-R_F, sm.add_constant(M)).fit()
but shouldn't be with the following formula?
AAPL_results = regression.linear_model.OLS(R-R_F, sm.add_constant(M-R_F)).fit()

I say this because the original formula for return is
R = Rf + Beta * (Rm - Rf).
resolving for Beta is
Beta = (R - Rf) / (Rm - Rf)

Thanks,

JM

@BenjiKCF
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BenjiKCF commented Sep 6, 2018

I find this weird too, I think it is not correct. Anyone can answer it? Thanks

@freddiev4 freddiev4 changed the title Beta calculation is correct in Lecture 30? Beta calculation is incorrect in Lecture 30? Oct 25, 2018
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