d2* Table
The constant d2* (Dee-Two-Star) is read from the Table called "Values for the distribution of the Average Range" given in the MSA Manual.
The values of d2* for reproducibility are:
For 2 appraisers : d2* = 1.41; K2 = 5.15/1.41 = 3.65
For 3 appraisers : d2* = 1.91; K2 = 5.15/1.91 = 2.70
Similarly, d2* used in repeatability calculations depends on No of trials and (No of parts time no of appraisers). So for
3 appraisers, and 10 parts we have the following d2* values:
for 2 trials : d2* = 1.128; K1 = 5.15/1.16 = 4.56
for 3 trials : d2* = 1.693; K1 = 5.15/1.72 = 3.04
For R&R calculations,
For 5 parts, d2* = 2.48; K3 = 5.15/2.48 = 2.08
For 10 parts, d2* = 3.18; K3 = 5.15/3.18 = 1.62
For statistical explanation of these values you will have to refer
"Quality Control And Industrial Statistics" by AJ Duncan.
-Atul.