Help Please Calculating Upper and lower control limits

Sue0113

Junior Member
Joined
Feb 1, 2012
Messages
114
Thefollowing data were collected on non-conformances
fora period of 10 days.
Day SampleSize Non-conformances
1 100 12
2 100 14
3 100 10
4 100 18
5 100 22
6 100 14
7 100 15
8 100 13
9 100 14
10 100 16
a. On what day isthe proportion of non-conformances largest? Day 5 smallest? Day 3
b. What are theLCL and UCL? Is there a formula for calculating this by hand?
c.Are there any special causes ofvariation? How do I answer this?
All calculations must be done by hand!

 
Thefollowing data were collected on non-conformances
fora period of 10 days.
Day SampleSize Non-conformances
1 100 12
2 100 14
3 100 10
4 100 18
5 100 22
6 100 14
7 100 15
8 100 13
9 100 14
10 100 16
a. On what day isthe proportion of non-conformances largest? Day 5 smallest? Day 3
b. What are theLCL and UCL? Is there a formula for calculating this by hand?
c.Are there any special causes ofvariation? How do I answer this?
All calculations must be done by hand!

Please share your work with us.

You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:

http://www.freemathhelp.com/forum/th...217#post322217

We can help - we only help after you have shown your work - or ask a specific question (e.g. "are these correct?")
 
Can't show work when I don't know

I can not show my work if i don't know how to calculate for LCL or UCL....I was asking if there was a formula!
I am looking for help as I have no clue what they are talking about...thought this was for homework help!
I read rules and this is not my first time here! I have asked specific questions.....Is there a formula for calculating LCL and UCL?
 
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I can not show my work if i don't know how to calculate for LCL or UCL....I was asking if there was a formula!
From the way you'd formatted your post, there was no way to tell that the question about the existence of a formula came from you, rather than being part of the exercise. Sorry.

I am looking for help as I have no clue what they are talking about...
Are you saying that the homework assignment is asking questions about material which has not been covered in class or in the textbook, so you are first needing lesson instruction?
 
Read:

hilo.hawaii.edu/uhh/faculty/furumo/documents/361Chapter6S.ppt
 
I can not show my work if i don't know how to calculate for LCL or UCL....I was asking if there was a formula!
I am looking for help as I have no clue what they are talking about...thought this was for homework help!
I read rules and this is not my first time here! I have asked specific questions.....Is there a formula for calculating LCL and UCL?
There are several ways to define Control Limits, and without more context I don't know what you are studying. That is why we need to see your work.

You need to find a measure of central tendency, and a measure of dispersion about that measure, and you have to choose the critical criterion.

1) You could write the values in increasing order, to find the median (central tendency) and the inter-quartile range (dispersion). Then the limits would be median ± (some number) times the (inter-quartile range). All that can be done by hand without even a calculator - so is that the method you should be using?

2) The other general method is to use formulas to find the mean and the standard deviation. That requires a calculator. The criterion is then expressed as some number of standard deviations away from the mean.

Look at the power-point presentation link given by Subhotosh Kahn for discussion of variations due to "natural causes" as opposed to "assignable causes."
hilo.hawaii.edu/uhh/faculty/furumo/documents/361Chapter6S.ppt
 
Calculation completed for LCL and UCL, can someone check if they are correct?

Would this be correct formula to use? How do you get formulas to copy in forum?
=148/100 = 0.148
=0.148 ± 3 square root of (0148)(1 - 0.148)/100
=0.148 ± 3 square root of (0.148)(.852)
=0.148 ± 3 square root of .00126096
=0.148 ± 3 =0.35509
=0.148 + 0.035509 = 0.18309 which is UCL
=0.148 - 0.35509 = 0.112491 which is LCL
Are these calculations correct?
For the 2nd part of question how do I know if there are any special causes of variation?



 
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