I am trying to follow this guide to calculate the p-value from an incidence rate between two samples.
The raw data is patients' use of an action plan before and after education.
Before education 7 uses over 44.17 patient years were observed.
After education 41 uses over 101.5 patient years were observed.
Totals are then 48 uses over 145.67 patient years.
So I think following the guide the chi^2 value is: (41 - (48*101.5)/145.67 )^2 ((48*44.17*101.5) / 145.67^2) = 5.627.
How can I go from this chi^2 value to a p-value? Most calculators I can find online require a Degrees of Freedom parameter, but I'm not sure what that means in this context?