Imagine we define Y(t+n)=Sum(X(t+1)+.....+X(t+n))$Y(t+n)= X(t+1)+.....+X(t+n)$ where X(i)$X(i)$ is an independent normal (i.e. everyday we remove the starting observation and we add a new one). We have N$n$ consecutive observations of Ys$Ys$. I am trying to find the expected number of changes in the sign in the sequence of Ys$Ys$ as a function of N$n$.
Thanks