1. The problem statement, all variables and given/known data This isn't really a question, its a report thing. Its about random radioactive decay. I have a histogram showing the number of counts recorded in 3 second intervals and I've drawn the Poisson Curve on the same graph. I have a graph for 50 intervals and one for 100 intervals and I need to analyse how well the data agrees with Poisson Distribution....and see if the 100 interval graph is any better than the 50 intervals. 2. Relevant equations n/a 3. The attempt at a solution I was thinking I should add up the differences between each bar on the histogram and the curve...subtracting the ones under the curve and adding the ones above. I'm sure this has a name in statistics and I need to know what it is - that's basically my question. What is the name of this graph analysis/statistics thing that I'm using? Or should I be doing something else???