This right here, this we could write that Q is a chi-squared distributed random variable or that we could use this notation right here Q is, we could write it like this this isn't an X anymore this is the greek letter chi although it looks alot like a curvy X so its a member of chi-squared and since we are only taking one sum over here here, we are only taking the sum of on 1 independent normally distributed standard normally distributed variable we say that this has only 1 degree of freedom. and we write that over here so this right here is our is our degree of freedom we have one degree of freedom over there. now if we define 