# Linearity Analysis - Measurement System Analysis - AIAG MSA Manual 3rd Edition

D

#### datony

linearity analysis (msa 3 edition)

i get questions on MSA Manual of 3rd edition. in the manual, in page 93, there is an equation to calculate the slope "a",from figure 11 in page 95,we get the value of "a" is "-0.131667",but i can't make this value out through the equation stated above using the data in table 5 and table 6 in page 94/95.
i wonder if the equation is wrong or the value from figure 11 is wrong? it has puzzled me for a long time since i read the 3rd edition.

Last edited by a moderator:
A

#### Atul Khandekar

Re: linearity analysis (msa 3 edition)

If I remember right, 2nd edition MSA used only bias averages(plotted on y axis) against Nominal values or levels (on x axis) for regression line. So if you have 5 levels, it used 5 points through which the regression line was drawn. Now, in the third edition, it uses ALL the points (g*m= 5 levels * 12 values at each level = 60 points).

D

#### datony

still have question

Atul Khandekar said:
If I remember right, 2nd edition MSA used only bias averages(plotted on y axis) against Nominal values or levels (on x axis) for regression line. So if you have 5 levels, it used 5 points through which the regression line was drawn. Now, in the third edition, it uses ALL the points (g*m= 5 levels * 12 values at each level = 60 points).

ok, I wonder if "xi" is the value given in table 5 in page 94, for example, x1=2.70, while "yi" is the value given in table 6 in page 95,for example, y1=0.7? But if I calculate these "a","b","s","ta","tb" using the "xi","yi" into the equations given in page 93,94, I can't get the exact value as given in the manual. I've calculate them in excel, the result is a=-0.14114,b=0.785969,s=0.2746,ta=-9.823,tb=8.496. I have sent you an e-mail on how can I make out these values which is different from these given in 3rd edition MSA. Please check it! The title of the e-mail is "linearity analysis" .
I know that the "a" and "b" is exactly the same in both the 2nd edition and 3rd edition MSA, but the equaltions are different,how could they make out the same values? I'm really puzzled about it, and hope you can help me! Thank you very much!

D

#### datony

I can't sent you an attatchment!

I want to sent you an e-mail on how I analyze the linearity,but i can't sent an attachment to you unless I get your e-mail address. My e-mail: [email protected], hope you can give your e-mail address to me.

A

#### Atul Khandekar

datony said:
I want to sent you an e-mail on how I analyze the linearity,but i can't sent an attachment to you unless I get your e-mail address. My e-mail: [email protected], hope you can give your e-mail address to me.
I sent you an email and a PM giving my email address.

D

#### datony

Atul Khandekar said:
I sent you an email and a PM giving my email address.
I've sent the attachment to you, please check it out!

M

#### Marie_2007

Bias Computation

Hello!

Could you please send me also a copy of the analysis for linearity? My e-mail ad is {e-mail ad Removed}. How about the analysis and computation of bias based on MSA 3rd edition?

Thank you.

Note:Your email ID was removed in order to prevent spam bots from harvesting emails from forums pages. Since you have enabled emailing from your user profile, members can contact you that way. - Atul.

J

#### jscholz

Re: still have question

ok, I wonder if "xi" is the value given in table 5 in page 94, for example, x1=2.70, while "yi" is the value given in table 6 in page 95,for example, y1=0.7? But if I calculate these "a","b","s","ta","tb" using the "xi","yi" into the equations given in page 93,94, I can't get the exact value as given in the manual. I've calculate them in excel, the result is a=-0.14114,b=0.785969,s=0.2746,ta=-9.823,tb=8.496. I have sent you an e-mail on how can I make out these values which is different from these given in 3rd edition MSA. Please check it! The title of the e-mail is "linearity analysis" .
I know that the "a" and "b" is exactly the same in both the 2nd edition and 3rd edition MSA, but the equaltions are different,how could they make out the same values? I'm really puzzled about it, and hope you can help me! Thank you very much!

Hi, I'm new to this forum, but this thread has caught my attention, since I have trouble with calculating a, b and s overall. I'm working with the 3rd Edition of MSA, but I'm noty able to calculate the correct results you mentioning. My results: a=-0.0328, b=0.1437, s=0.09614, ta=6.5203, tb=1.56153. It seems I misinterpret the formulas on page 93 wrong; can you give me some advice? I'm using Excel. Thanks.

#### Miner

##### Forum Moderator
Try the Excel file MSA 3rd Ed.xls in this thread.

There is a tab for the linearity study. The calculations are in the columns to the right with the text turned white. Just select a large section an color the text black to see the formulae.

J

#### jscholz

Try the Excel file MSA 3rd Ed.xls in this thread.

There is a tab for the linearity study. The calculations are in the columns to the right with the text turned white. Just select a large section an color the text black to see the formulae.

Thanks for your quick response. That will help me a lot.