Why did you do this? ie why do you want to make the data ‘Normal’ ?
It doesn’t help you solve the problem.
Counted data will not be normal distributed in general.
And no: I would not trust any data manipulated in this way.
Remi replied to the topic Calculating Process Capability for Wait Time at a Restaurant in the forum Methodology 12 years, 3 months ago
whenever I have a data set that contains a lot of 0’s I split my capability analysis of the CTQ in two.
CTQ1= % non-zero’s; Target is very often 0; goal of project part1 to reduce average value and variation of CTQ1
CTQ2 = CTQ if CTQ is non-zero. target = 0; goal of project2 to improve Cpk and reduce values.
By splitting this up…[Read more]
Hai The Kid,
You can’t. A gage r&R study is an experiment you do to investigates the quality of your data-collection/measurement. Unless you can perform that experiment you cannot do a gage r&R.
This doesn’t mean that your old data is worthless. only that you can’t proof that it can be trusted.
So the only way forward is: Write down in your r…[Read more]
as a first approximation you could sum them up.
More correct is to compensate for products that have more than one characteristic failing. If the characteristics occur independently of each other you get the following calculation (if not a similar formula can be derived but you have to count the multiple occurences).
Pi = P (char i…[Read more]
No, Boxplot does not use normality; it is distribution free. What happens is: IF Data is Normal distr. THEN (1.5*IQR and 3* Stdev give the same value) and (Median and Mean give the same value). So in that case points further than 1.5*IQR happen to cross the +/- 3S line.For detecting potential outliers mathematicians have calcu…[Read more]
You already wrote in your message a solution: the problem (as seen by you) is created by Sales that has to get to target in Q4.A simple (uncacceptable by Mgt?) solution is to arrange for Sales Quarter targets. Then your Year problem changes into a Quarter problem. If that is still too rough change it into a Month problem etc.
Better i…[Read more]
for a Six Sigma project you generally only use the tools that you need (for making the project a success). Since nobody knows beforehand which those will be a lot of them are covered in the GB course .
if you are doing a six sigma project to get certified, the certifier wants you to show him/her that you are Capable of doing Six…[Read more]
distributions don’t have outliers, whether normal or not.
If you mean “how can I see if a data-point is an outlier in a data set that does not follow a normal distribution”:
– make a graph (dotplot, histogram,…)
– if you see a point ‘far away’ (purely subjective eyeball mark1 measurement) investigate WHY that point is different…[Read more]
make a process mapping (=flow chart) of the process steps.There is 1 input location (=entry).Put 1.000.000 product(part)s in the process entry. Write down for every process step how many parts (of the 1.000.000) enter that process step (calculate from parallel-split-up) and how many leave the process step (calculated from RTY of…[Read more]
the correct answer is: it depends.
If y = air usage, it does not matter how the holes are placed. The air usage is the Area of all the holes together.
If Y = cooling strength on a small area, then situation with holes all near the centre gives a different result than holes on the border.
So the question is: what is your Y=CTQ and how…[Read more]
here is a way to do it.
Input is LSL, T(arget), USL.
1] you have to choose a formula for the loss-function. THE LOSS-FUNCTION does not exist (as far as I know); an often mentioned one is the quadratic form L=K*(y-T)*(y-T) where the K is the loss-factor. If you have T = (USL+LSL)/2 (i.e. in the middle) you can determine K if you…[Read more]
Ask your experts to give a score on the quality of the mark on a scale of 1 to 10: a “5” is considered perfect marking; a “1” is for ‘burned’ and a “10” is for ‘no mark’. In this way you have a ranking of the laser marking from ‘too much’ (1) through ‘good’ (5) until ‘too little’ (10).Use this score as the Y of your DoE analysis a…[Read more]
I don’t know your template but general the answer is NO.
First a warning: be carefull with the sentence “to measure the Gage R&R of the QC technicians”. Operator is only part of the variation sources. A gage r&R investigates the consequences of all variation source of measurement variation (that happen during the experiment). So if…[Read more]
in my answer I mentioned that the residuals should be normal distributed. Y= f(x) + error; the ANOVA analysis can be usedIFF ((error is normal distributed) AND (equal variances test is passed)).
I realize that “error is Normal” is not exactly the same as “each of the groups is normal” but don’t remember enough of my statistics to say…[Read more]
So you have 2884 lengths of fishes divided over 8 groups.
First make a picture: boxplot and decide if you want to perform analyssi on all the data or if some of the points should be analysed different.
Then do 1-Way ANOVA.
The data itself does not have to be normal distributed (and often is not if there is a large mean-difference); but…[Read more]
Sorry Sathya, but your explanation of boxplot-conclusions is WRONG.
Duplicate the datasets sever times (make sample Size artificially high). The boxplots will not be different; the Mean and StDev do ‘not’ change; but the p-values will get arbitrary low: the larger you make the N the smaller the P-value gets.
I expect that all your managers will have moved to a new job before you have enough data with only 4 data/year.
Forget this approach and put all your effort into finding a way to get data more often (and of the contiuous type). The good news is that you have at least 3 months before the next datapoint makes your question a little bit…[Read more]
yes and No. You could do it but the 3d factor may influence the result as a lurking factor.
Suppose your ‘real (unknown) model’ is: Y= X1 + X2 + 20*X3 + 100*X1*X3If you leave out the significant X3 two things happen (both bad for conclusions):
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