Thaly replied to the topic Building a statistically valid model for projection in the forum General 15 years, 11 months ago
I’m afraid your question is a very generalized one.
If you want to do some forecasting, you could use some time series models. Or if you want to build a model that could predict an outcome based on the input variables there are a number of tools to do that. Regression is one, Neural networks is another, decision trees could be built. The model…[Read more]
I’m not sure if you could get Z from Ppk alone.
May be you could try to transform your data and fit it to a normal distribution and see if it fits better.
Do you know what shape parameter you used? If you could calculate mean,(and then from Ppk and spec limits, you could calculate sigma) then you could calculate your z value.
do post it if…[Read more]
You need to know your mean and sigma (and your spec limits) to calculate z.z = (USL – mean)/ sigma.z = (mean – LSL)/ sigma.If you know your Ppk and any one of your variables (mean or sigma) then you could calculate the other and use those to calculate Z.
Hope this helps.
Are you convinced that any kind of PMs dont work for you? I don’t believe PFMEA is the right way to approach your problem, and I work in a very similar type of company as you. There are no documented benefits of using APQP as far as I know. I like to think of APQP as purchasing automobile insurance. If you have an expensive vehicle and you are an…[Read more]
I mistook your talking about Gage Master to be GRR. What you say about masters is right. Yes, your master sample must be fixed and you should know the dimensions of the master(or atleast the ones you are interested in), so that you could offset your gage by the specified value everytime. (If you are using a transducer equipped digital…[Read more]
Your n is 4 and you’d have 4 different control charts for each of your PCBs. (This is if you are treating the individual PCBs as separate entities.)
You do not have to compute the CPk each time, because you are already using a control chart, and if the points stay within the limits, you already know your process is in control.
I think you…[Read more]
The 6 sigma logic won’t apply to your scenario unless you know that the deaths are distributed normally (or atleast close). Usually such discrete events resemble more of a Poisson distribution (or other discrete distributions).
If you have the right tools, you could build a neural network model (or a regression model) of your death/plane crash…[Read more]
All of the answers you got are good. here is a little mathematical explanation.
You calculate ndc as follows: (5.15*Sigma-Process)/(2.575*1.414*Sigma-meas)The numerator is fairly easy to understand. The denominator is basically the discriminatory power of the gage. Lets say you make 2 measurements X1 and X2. Now the absolute difference between X1…[Read more]
I understand you are doing a 100% inspection.
One way to improve your gage R&R is by looking at the control limits of the R&R experiment and attack the points out of control due to operator error. (Reproducibility). see if you could get all the points within the control limits. This brings down the operator error part of your R&R. If you can’t…[Read more]
I agree with juggler. I’d recheck my numbers if I had a situation like that. The most likely situation is that the noise was very high during the experiment. Try doing more replicates or seprating the factor levels further.
But to answer your question, you’d have to include all the non-significant main effects that contribute to the interaction…[Read more]
Unless you want to include the suppliers of the 6 variety of inserts as a factor, it is not a nested ANOVA.
You could just do a general full factorial design. One thing to note is that your experiment looks like it could be affected by not randomizing the experiment, since running that many parts might amplify a lurking variable and…[Read more]
I’m performing a DOE and I’m unsure on deciding whether my runs as such are replicates or repeats. The parts on which the response is meaasured is coming out of a forge press line (response is straightness of the features in the part). So if I take three successive samples out of the product line for each treatment(setting the appropriate levels…[Read more]