Sample Size Calculation.

[former_member351306]

Hello

I've a question on how the system calculates the sample size ie., what is the math involved. Here is the scenario.

Inspection plan - with 3 operations.

Inspection plan has sampl procedure without sampling scheme, fixed sample, wihtout inspection points, valuation mode is 'mean value withiin tolerance range', no muiltiple samples, sample size is 1 and the plan does not have sample drawing procedure or dynamic modification rule.

Operation 0010 - 2 qualitative characs, partial sample no. 1.

Operation 0020 - 2 quantitative characs, partial sample no. 2.

Operation 0030 - 1 qualitative characs, partial sample no. 3.

Create a manual inspection lot fo size 100 EA, the sample size calculated by the system is 4 EA - how did the system arrive at this number? I checked the functiona module QDRS_FIXED_SAMPLE behind the determination rule 10 (fixed sample), maybe I should ask a developer to look into it, but I did not see any calculation.

thanks

BE

[Former Member · Accepted solution]

By std SAp the sample size of the inspection lot is maximum of the sample sizes of the individual MIC's.

Now what you have to check here is.

1.check the individual sample size of each mic.You can see this in result recording screen.

2.Second is check whether you have selected any control indicator like "destructive" or additive" sample for any mic.

possibly you have !!

what is " partial sample no. 1." 2,3 etc ??

[former_member351306 · Accepted solution]

Hello Sujit

Thanksfor the response - here is my reply to the questions you raised.

1. In results recording screen all MICs show sample size of 1.

2. Partial sample number (or partial samples) is assigned to each MIC in the inspection plan and definition from F1 is 'Number of a partial sample that is assigned to the inspection characteristic in the task list'.

3. None of the MICs are marked for 'additive' or 'destructive' in their respective control indicators.

Pl. let me know if you want me to check something else and appreciate your help.

thanks

BE.

[Former Member · Accepted solution]

Operation 0010 - 2 qualitative characs, partial sample no. 1.

Operation 0020 - 2 quantitative characs, partial sample no. 2.

Operation 0030 - 1 qualitative characs, partial sample no. 3.

Create a manual inspection lot fo size 100 EA, the sample size calculated by the system is 4 EA - how did the system arrive at this number?

Here is explaination.

Generally Partial sample concept is used in case of sample management.Means when you have "sample drawing in place.

But if you are suing this without sample management then,

The total sample quantity for an inspection lot equals the total sum of the quantities of all partial samples.

The system determines the quantity of each partial sample from the largest sample quantity of all the characteristics that are to be checked using a particular partial sample.

Now what remains to check is whether all the MIC's are " required "char or 1 or 2 of them are "optional"....check control indicators.

This will lead you to calcualtion.

[former_member351306 · Accepted solution]

Hello Sujit

All the characteristics are set as 'required' in the control indicators and none of the MICs are set as 'additive' or 'destructive'. What else should I be checking?

thanks again

BE

[former_member42743 · Accepted solution]

Have you tried it without putting in the partial sample indicators? What is the result?

FF

[Subh · Accepted solution]

Hi Brian,

In a scenario without "additive" or "destructive" indicators, SAP staes For a partial sample that is used for several characteristics, the system takes the largest determined sample quantity as the partial sample quantity.

As per that in your case total sample should be 111= 3

If you sre getting 4, there may be something else we are missing out. Please check in your sampling procedure whether for any procedure the sample size is 2.

Regards

Sm.

[former_member351306 · Accepted solution]

Hi

Without putting the partial sample number, system calculates the sample size as '1'. However, in operation 0020 there are couple of more qualitative MICs which do not have the partial sample number assigned and when I assign the partial sample number '2' to these two MICs, the system now calculates the sample size as '3' (whcih is what I wanted to see in the first place) in the inspection lot. I retested again removing the partial sample number for these two qualitative MICs in the operation 0020 of the inspection plan and the new inspection lot now returns a value of 4 for the sample size. I still do not understand as to how the system is returning 4 as the sample size, but, apparently the issue is with the partial number in the operation 0020. If anybody can explain this phenomen, I'd be grateful.

However, I want thank everybody for their inputs and suggestions.

All the sampling procedures assigned to the MICs in all the operations have a sample size of 1.

thanks a lot.

BE.

Edited by: Brian Elfie on Sep 3, 2011 5:03 PM

Edited by: Brian Elfie on Sep 3, 2011 5:07 PM

[Former Member · Accepted solution]

I think from your last explaination I got the answer......

Operation 0020 - 2 quantitative characs, partial sample no. 2

Means operation two has the largest number of partial samples & sum of these two partial samples would be the sample size.

(2+2=4) if you try to change it to 3 each then i am sure system will calculate it as 6 .....

[former_member42743 · Accepted solution]

Actually since both tests should be sharing the same partial sample number, it should still be 2 regardless of the number of characteristics in the operation. Now if he gave one of the characteristics a partial sample number of 2 and the other no partial sample number, than it might 4. I've never tried that.

[Subh · Accepted solution]

Hi Brian,

In standard SAP physical sample planning requires sample drawing procedure.

Link: [http://help.sap.com/erp2005_ehp_05/helpdata/EN/2d/3521b6448c11d189420000e829fbbd/frameset.htm]

And drawing procedure is advised with partial sample numbers.

Link: [http://help.sap.com/erp2005_ehp_05/helpdata/EN/2d/3521b6448c11d189420000e829fbbd/frameset.htm]

Generally when we use partial sample numbers, we also use a drawing procedure. And in that scenario SAP describes the calculation as shown in

Link: [http://help.sap.com/erp2005_ehp_05/helpdata/EN/2d/3521b6448c11d189420000e829fbbd/frameset.htm]

What you have done (partial samples for MICs and not having for others, all without drawing procedure) is not generally done. I think our observations in this context should be confirmed only if we try more of such examples.

Regards

Sm.

[former_member42743]

From what you have indicated, I wouild have calculated a total sample size of 1.

The partial sample nos, should have no impact on the calculation as you are not using a sample drawing procedure.

So somewhere you have a setting not yet known.

Do any of the MIC's have the control indicators "Additive" or "Destructive" ticked on? Check these in the inspection plan.

FF