i was taught, that SPC Charts need a normal distribution.

However i have thought all the time, that it is not inevitably necessary.

Then i found the following article:

https://www.qualitydigest.com/inside/lean-column/control-charts-keep-it-simple-121818.html#

What do you think? What are your thoughts?

Best Regards

Peter]]>

I have just finished my core tools training. I would like to dive into the SPC domain to get a better handle on it.

Can anyone suggest any website where I can get any exercises for playing around in minitab for the SPC?

I will start work in parallel for values over at work but I would appreciate any help from the theoretical side at least. It would jump start my SPC exercises until I will have the values collected for the work field over at my place]]>

I have a process parameter that is controlled this way:

If the equipment signal response is below a certain level, we know for sure that the result will be lower than 10% and thus reported as <10.

However, if a signal response is a little bit higher, then I have to actually quantify the value. In this cases, I usually get results around 5-6, which are still below the 10.

My data distbitution is something like this:

Sample size - 126

Analysis result | Number of events | Cumulative...

Apply control limits to a non-normal distribution]]>

How can I manage the defective rate in this situation?]]>

One of our customers requires SPC. As we do not have any experience with this subject I'm currently reading a lot about it and experimenting in Excel.

In our production process we perform measurements to release batches, this is done at the end of the process. I have gathered some data to experiment with calculating Cpk and Ppk.

For a certain product I have data from three different days, total 36 values. For the calculation of Ppk I take the standard deviation of the whole...

Calculation of Cpk]]>

Can you please point me out an appropriate control chart for this scenario?

Thank you in advance.]]>

I have a detail, I do a series of measurements of the hole diameter - 200 measurements = pieces. How to group data to create a control card. I mean test numbers x1, x2, x3, x4, x5 etc - these are the columns. How do I sort the data in rows? Is it just a series of consecutive measurements?

I will be happy to help. Regards]]>

I'm starting with SPC in my company. To my understanding to run SPC you need first to set up what I call the benchmarks (UCL and LCL) using a set of historical data. Once this defined you plot all new values against those and check for OOC results.

My colleagues use to run statistical on the data and where looking also for OOC points. Doing like this you get moving UCL and LCL. They don't use historical data.

What is correct practice ?

Regards,

Guy

Please excuse my English, it...

Understanding SPC]]>

I am in need of some guidance. I have been tasked to show incidents that have caused harm per 1000 occupied bed days in the form of a u chart. The problem I have is trying to show it as per 1000 occupied bed days as when I try to throw in a multiplier the UCL and LCL lines become very small. Can anyone advise on how I can get the graph to show per 1000 occupied bed days? I have attached how the chart looks with the multiplier. Any guidance is greatly appreciated!

Regards,

Saif.]]>

I was assigned a task in the company I work for related to evaluate control limits from SPC charts periodically (yearly). The evaluation is to determine if control limits recalculation is required... this is easy for me to do in terms of reviewing a few charts... the problem is that there are around 5000 SPC charts in all the plant so my manager is asking me to define a "valid" criteria to choose some charts and evaluate them. At the end we are looking to have SPC charts with...

Control limits evaluation / recalculation]]>

We just had a vice presidential debate. Since my null hypothesis is my dull hypothesis, I submit the following two:

H0: The vice-presidential debate had no effect on voter decision.

HA: The vice-presidential debate changed the minds of voters.

So under the assumption I do all the surveying and statistical math right looking for a changed poll after the debate.....

What does the p-value mean?]]>

Could someone help me with an interpretation of the following Capability Six pack result? Please look at the attached file.

I am aware that there is only 32 observations instead of at least 50, but in this case there are enough to determine that the process needs to be changed.

Individual and Moving Range Charts should be ok. I used in Minitab the Nelson Rules feature and there are any red points. It could be said that the process is stable.

Capability Histogram...

Interpret the capability plot in Capability Six pack]]>

Thanks]]>

I intend to use Minitab, but before using, i would like to know the following (what i can not get from the available videos):

My intension is to evaluate a process - how much an actual process differs from the master measurement. Every measurement has the following format:

------------------------------

Measurement 1:

x ............ ... y

300 ............ 50

350 ............ 55

400 ...............

How to evaluate any significant difference using Minitab]]>