Why adding metrics

I remember using metrics=[‘accuracy’] in model.compile in last courses to get the accuracy. however it does not work in C4_W2_lab2. Would you please explain why it does not work here ?

C4_w2_Lab_2 refers to building a regression based time series model. Metrics like accuracy are meant for classification models. Use metrics like mae.

Thanks! One more question, why dense layer does not have and activation? If we don’t mention it does it mean the activation is linear ?

That is correct. A dense layer without activation defaults to linear.