A hospital is analyzing nosocomial infections and wants to reduce their infection rate below the national average of 2.0%. They have sampled 40 cases every week for the last 20 weeks. The data are shown below. Create p and np control charts. Interpret the graphic.

I think I am messing up on the calculations. I know the formula: UCL: p+3 square root (p x q) / n I am getting 0.067 + 3 square root 0.067(0.933)/ 40. not sure if I use 40 sample size or am I using 800.

Sample Infection

1 2

2 1

3 1

4 2

5 1

6 1

7 3

8 2

9 1

10 2

11 3

12 4

13 2

14 3

15 4

16 5

17 3

18 4

19 5

20 6