# Getting values of k1, k2 and k3 for n=30, r=3 and k=3

#### Rameshwar25

##### Quite Involved in Discussions
Our customer is asking for GRR study (Av and Range method) for 30 parts. Can someone help me in getting values of k1, k2 and k3 for n=30, r=3 and k=3.

rameshwar

#### Bev D

##### Heretical Statistician
Staff member
Super Moderator
adn the d2 value for 30 parts is not listed in any published tables. however at this number of parts you are better off calculating the standard deviation of the parts directly usign the standard deviation formula and not the range...

#### Gopalselva

##### Registered
Our customer is asking for GRR study (Av and Range method) for 30 parts. Can someone help me in getting values of k1, k2 and k3 for n=30, r=3 and k=3.

rameshwar
Our customer is asking for GRR study (Av and Range method) for 30 parts. Can someone help me in getting values of k1, k2 and k3 for n=30, r=3 and k=3.

rameshwar
Sir, did you have answer i have also same doubt

#### sealteamrick87

##### Starting to get Involved
I am also new to this and do not understand how to calculate this as I have never had any training on this. How is it possible to calculate the "K" values for 30 parts?

#### sealteamrick87

##### Starting to get Involved
Sir, did you have answer i have also same doubt
Look into QI Macros for Excel. Very useful software for this.

#### Bev D

##### Heretical Statistician
Staff member
Super Moderator
with a large number of repeated measurements you shouldn't use the range. you need to use the standard deviation.
1) the range tables do not go beyond n=25 (commonly available tables do not go beyond n=10.) because the formula for d2 is horrendous.
2) the standard deviation is MUCH more precise at large sample sizes (n>3-5) because it uses all of the data and the range only uses the min and max number.

Of course to do this without statistical software you need to understand the formulas - you can't treat Gauge R&R as a black box.