For my local charity I have to organize random draws, each week to give a prize. I just bought a random machine generator, which randomly spits one ball out of 10.
Before using the machine in public I made some tests in private to ensure that the machine is properly random and I am not accused of cheating.
So I made about 1300 random draws and performed a chisquare test.
I got the following chi square value: 18.13
Since there are 10 possible outcomes, there are 9 degrees of freedom.
Here are the values for 9 df:
ν 0.100 0.050 0.025 0.010 0.005 0.001 9 14.6837 16.9190 19.0228 21.6660 23.5893 27.8772
18.13 is greater that 14.6 and 16.9 does it mean that I am 95% confident that the machine is not random and I should change it? Or is 1300 experiments not enough to make a conclusion?