F Ratio (Obtained F Statistic) Now we get to take the two parts of the fraction that you calculated above and figure out what our actual F Ratio is and to find out IF we have a significant effect with our homework groups. F ratio formula First, calculate your F Ratio S2Between = S2Within = F Ratio = S2Between / S2Within = Find the Critical Region (where significance STARTS) To see if our F Ratio is significant, just like we did with the t-Test, we can compare it to the value that "starts" the critical region. Below is the table we will use. The concept of the critical region is the same here as it was with the t-Test but the table is a little different since we have TWO df values and the distribution is that positive skewed one rather than the symmetrical bell curve that we see with the t-Test. To determine that our F Ratio is significant, it needs to be a higher value than the critical region value. Note: Top row in yellow is dfBetween First column in yellow is dfWithin Find the value that aligns with both df values F distribution critical value chart Results What is our critical F value? What is our obtained F value? Decision: is our result significant or not significant