Activity

Robert Butler and Katie Barry are now friends 6 months, 2 weeks ago

Robert Butler replied to the topic Probability of an Average for a Group Based on Individual Value Distribution in the forum Tools & Templates 6 months, 2 weeks ago
I think you will need to provide some additional details.
1. In your first post you are talking about weight and in your second post you are talking about height – which is it?
2. In your first post you will need to clarify what you mean by “I have a normal distribution for a coating weight per part of 1 gram/m2 and a standard deviation of…[Read more] 
Robert Butler replied to the topic Gage R&R with One Part, One Operator, 10 Tries in the forum Tools & Templates 6 months, 3 weeks ago
No, it’s not a case of the less you have of repeated measures the less precision you have on the value of the standard deviation of the GRR rather it is a matter of the less you have of repeated measures the better the precision of your estimate of the true value of the standard deviation of the GRR. As I said – repeated measures variation will…[Read more]

Robert Butler replied to the topic Gage R&R with One Part, One Operator, 10 Tries in the forum Tools & Templates 6 months, 3 weeks ago
In addition to what @cseider said you also do not have independent measurements – you have repeated measures on a single item which means your estimates of variation are going to be much less than the real variation you can expect in your process.

Robert Butler replied to the topic How to Analyze Nonnormal Data and Indicate the Capability of the Process? in the forum Tools & Templates 7 months ago
I’m not trying to be funny at your expense but if you really have a process like this then then next Nobel Prize in Physics will be yours on demand because you have found a process that exhibits zero variation which means you have invalidated the second law of thermodynamics – something that heretofore was deemed physically…[Read more]

Robert Butler replied to the topic Need Help Analyzing NonNormal Data in the forum Tools & Templates 7 months ago
I would recommend you reexamine your data. The IMR plot gives a visual impression of three distinct shifts downward in your data. The first cut point occurs at about data point 44, and the second at about data point 83. It also gives the impression the process is drifting back toward the target around data point 93. In short, the plot would…[Read more]

Robert Butler replied to the topic Why Are Linear Plots Mostly Used in Regression? in the forum Tools & Templates 7 months ago
I’m not trying to be sarcastic but who is making the claim that linear plots are mostly used in [an examination?] of a linear regression?
There are any number of reasons why an analysis might result in employing simple linear plots. For example:
1. Your plan for analysis involves running a two level factorial design. – In this case, by…[Read more] 
Robert Butler replied to the topic Need Help Analyzing Variance with Minitab in the forum Tools & Templates 7 months, 1 week ago
I see I spoke too soon. What I said above still applies with respect to the graphical presentation and sampling plan you should use when repeating your test but since you provided the actual data there are a couple of other things to consider.
Again, if we pretend the sequential measures within a given operator are independent (they’re not)…[Read more]

Robert Butler replied to the topic Need Help Analyzing Variance with Minitab in the forum Tools & Templates 7 months, 1 week ago
I don’t know Minitab but I do know they have boxplots graphics which I would recommend you use. You would have sidebyside boxplots of the two shifts. What you will want to do is to make boxplots which also shows the raw data that way you will not only have the boxplot with its summary statistics but you will be able to see visually just how…[Read more]

Robert Butler replied to the topic Need Help Analyzing Variance with Minitab in the forum Tools & Templates 7 months, 1 week ago
Just a visual impression of your data says you have a statistically significant difference in mean scoop size between first and second shift. If we check it formally and pretend the measures within each team member can be treated as independent measures then what you have is 1.22 vs 1.88 (which, given the limit on significant digits reduces to…[Read more]

Robert Butler replied to the topic What Was Your Career Path Into Process Improvement? in the forum General 7 months, 2 weeks ago
Wellll…not counting the mandatory military service I don’t think there’s been any time in my career when I wasn’t involved in process improvement. I started off as a physicist working in advanced optics – the work was a combination of R&D and improving existing systems/processes. One of the groups I worked with had an assigned statistician. I…[Read more]

Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 7 months, 2 weeks ago
You’re welcome. I hope some of this will help you solve your problem.

Robert Butler replied to the topic Hypothesis Testing in the forum General 7 months, 2 weeks ago
I don’t know the basis for your statement “I know that in order to be able to do the Hypothesis Testing we must also be able to test for Normality and the “ttest”. but it is completely false. There is no prerequisite connection between the desire to test a random hypothesis and ANY specific statistical test. Rather, it is a case of for…[Read more]

Robert Butler replied to the topic What Are Your GoTo ProblemSolving Tools? in the forum Tools & Templates 7 months, 3 weeks ago
As Kaplan put it in his book The Conduct of Inquiry, ” When attacking a problem the good scientist will utilize anything that suggests itself as a weapon.” :)

Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 7 months, 3 weeks ago
If we couple what you said in your last post with an assessment of the graphs you have generated I think you might have the answer to your question.
As I said previously, the normal probability plots of cycle time days by department is a very important graph. What it shows is that the cycle time data for 4 out of the 5 departments is…[Read more]

Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 7 months, 4 weeks ago
There’s no need to apologize. You have an interesting problem and I just hope that I will be able to offer some assistance. To that end, I may be the one that needs to apologize. I was rereading all of your attachments and, in light of what you have in the most recent attachment, I’m concerned that my understanding of your process is…[Read more]

Robert Butler replied to the topic What Is the Origin of Measurement System Analysis (MSA)? in the forum Tools & Templates 7 months, 4 weeks ago
As @Straydog has noted references to standards in measurements has a very long history. The link below suggests referring to such checks as MSA occurred sometime in the 1970’s
https://www.qdas.com/fileadmin/mediamanager/PIQArtikel/History_MeasurementSystemAnalysis.pdf

Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 7 months, 4 weeks ago
A few general comments/clarifications before we proceed
1. You said “I guess I was looking at the pvalue because I know that would determine the kind of test I run eventually.” I assume this statement is based on something you read – whoever offered it is wrong – pvalues have nothing to do with test choices.
2. When I made the comment about t…[Read more] 
Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 7 months, 4 weeks ago
The histograms and the boxplots suggest some interesting possibilities. Based on what you have posted I’m assuming your computer package will not let you have a boxplot which includes the raw data. On the other hand, if there is a subcommand to allow this you really need to have a plot that shows both.
If my understanding of your process is…[Read more]

Robert Butler replied to the topic Hypothesis Testing – Levene's Test or Moods Test? in the forum Tools & Templates 8 months ago
If your post is an accurate description of your approach to the problem then what you are doing is wrong and you need to stop and take the time to actually analyze your data in a proper statistical manner.
The first rule in data analysis is plot your data. If you don’t know what your data looks like then you have no idea what any of the tests…[Read more]
 Load More