- 20. same thing, if you knew this one over here, this one is not new information. similarly,if you knew these two, this one here id not new information. you can calculate this based on the total and everything else. so that's the sense as to why the degrees of freedom are the columns - 1 times the rows - 1 . so any way, our chi square statistic has two degrees of freedom. so remember our alpha value is 10 %. so we are going to figure out what our critical chi square statistic is that gives us an alpha of 10 % and if this is more extreme than that, if the probability of getting this is even less than that critical statistic, we can reject the null hpothesis, and if it is not more extreme, we will not reject the null hypothesis. so what we need to do is to figure out what the chi square distribution is and 2 degrees of freedom, what is our critical chi square statistic. so lets just go back, we have two degrees of freedom here and we have a care about a significance level of 10 % so our critical chi square value is 4.60. another way to visualize this is if you look at a kai square distribution with 2 degrees of freedom, that is the blue one over here, at a value of 4.60, the probability of getting something atleast that extreme is 10%.this is what we care about. 