I have built an ARMA model on the stock index log returns.

but I found the residual of the model is not Normal distribution but no
autocorrelation which means the residual maybe is weak white noise(Can I say
that?) instead of Gaussian white noise.

If the residual is weak white noise, can it pass the diagnostic tests in
the Box-Jenkins Procedure?
the Test result is :

Normality test: Chi^2(2) = 1590.9 [0.0000]**
Portmanteau(50): Chi^2(48) = 101.43 [0.0000]**
--------------------------------------------------------------------------------------------------

BTW, I always found the constant in the model can not pass the t-test,
should I omit it in the ARMA model or just leave it in?

	[[alternative HTML version deleted]]

