R Chart with probability limits

[abhipatel]

Am all confused...W is the relative range right?
Where do we get the value of W from - which table... proff got
W0.999 = 5.483754 & W 0.001 = 0.367392
(Que: Suppose we want to use probability limits with α = 0.002...sample size is 5)
Please help & explain.

 

[Pere Callahan]

I have no idea what you are talking about. Please try and formulate your question in a more understandable way.

 

[abhipatel]

Suppose we want to use probability limits with α = 0.002. What are the control limits for theX and R charts?

Sample size is 5...All I want is how do we calculate R limits

Solution : W 1 - α/2 = W0.999 = 5.483754

Just want to know what table he has referred to get this answer?