i need help to find out if my series include seasonal effect. I am trying to test with dummy variables? As i learned before in monthly data i have to use 11 dummies and estimate this equation

y d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11

Here are my questions ;

- is constant should take a part in this equation? like (y

**c**d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 d11)

- what the f values have to be if there is seasonality?

Thanks and b. regards