Hi, what are the center points? They have same coordinates but their responses are different. Why? What happens if I increase or decrease the number of center points? I can not visualize center points in central composite design.
Thank you for this video. May I ask if the axial points in the CCD is considered included in the Design Space? I am using a software where it warns me that axial points are not part of the Design space. I don't understand.
Hello, what do one do, in box behnken design when the number of response is less than the total numbers of run. Pls i would appreciate your speedy response sir. Cheers
Thanks a lot for this wonderful video and smooth explanation... I was just wondering how to set the actual values in relation to the coded values of the levels (-1.41,-1,0,1,1.41)?? For example if my factor is treatment time(from 0min "low=-1" to 5min "high=1", and I would like to run a face centred design, could I relate the 0 level to 1min treatment time? or should it be exactly in the middle of both low and high values (2.5min in that case)?? Please advise
If your range is 0 min to 5 min, then the "-1" level will be 0min, and the "+1" level will be 5min. Everything is linear from there. So, a "0" level would have to be 2.5min.
Hello sir, Hope you are fine. I want to use this software for my article. but can you tell me how can I download it? Is it paid or free? please let me know more information about this software! Thank you for your time.
Thank you. Very clear and helpful video. I have one question: if rotatability is a property we're looking for, is a Circumscribed Design always prefered over a Face Centered Design?
We care about many properties, not just rotatability. Often, practical issues affect design choice, like the allowable range of variables. For circumscribed design, the "star" points use larger variable ranges.
Thank you for sharing this video. It's answered a lot of questions for me. You said the centre points are repeated in order to detect shifts. How exactly do we determine if there is a shift?
look at your center points raw data and evaluate the noise (Standard deviation or CV) or look for the Pure error term in your DOE analysis in Mintab or whatever software you use. Pure error is the error obtained from repeated measurements such as your center points.
I’d think you’d need an already prepared control chart in place to check that the centre points (4 say) were between the control limits. You couldn’t detect a shift (step change or trend) from just 4 points alone. However, the 4 points can be used to calculate uncertainty of the effect values (what you’d call partial replication as only one of the runs/treatment combinations is replicated) and you’d want the variation of the 4 points to be smaller than the variation between the levels for each factor otherwise the factor effects are unlikely to be significant. That’s my best guess at an answer.
Thank you for sharing this video. It's answered a lot of questions for me. You said the centre points are repeated in order to detect shifts. How exactly do we determine if there is a shift?
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Sir, you have just helped me to learn this topic clearly, from miles miles away.
With my best regards.
this is a great, straightforward explanation of a complicated topic - thank you!
best explanation. You are really a professor.
Very clear and helpfull. THNKS
It was a very good and well explained
Hi, what are the center points? They have same coordinates but their responses are different. Why? What happens if I increase or decrease the number of center points? I can not visualize center points in central composite design.
Thank you for this video. May I ask if the axial points in the CCD is considered included in the Design Space? I am using a software where it warns me that axial points are not part of the Design space. I don't understand.
Hello, what do one do, in box behnken design when the number of response is less than the total numbers of run. Pls i would appreciate your speedy response sir.
Cheers
I can choose central composite face centered?
Great explanation! Thank you very much for doing this!
Thanks for this it is very helpful
it was helpful. keep posting more.
Thanks a lot for this wonderful video and smooth explanation... I was just wondering how to set the actual values in relation to the coded values of the levels (-1.41,-1,0,1,1.41)??
For example if my factor is treatment time(from 0min "low=-1" to 5min "high=1", and I would like to run a face centred design, could I relate the 0 level to 1min treatment time? or should it be exactly in the middle of both low and high values (2.5min in that case)?? Please advise
If your range is 0 min to 5 min, then the "-1" level will be 0min, and the "+1" level will be 5min. Everything is linear from there. So, a "0" level would have to be 2.5min.
Thanks alot :)
Is the central composite design = face centered design? Different names for same concept?
There are three types of central composite design - face centered design is one of them.
Hello sir, Hope you are fine. I want to use this software for my article. but can you tell me how can I download it? Is it paid or free? please let me know more information about this software! Thank you for your time.
Go to the main course content site (www.lithoguru.com/scientist/statistics/course.html) and look at the links for Lecture 0. The R software is free.
Thank you so much.
Hello, can I use alfa = 1?
Thank you. Very clear and helpful video. I have one question: if rotatability is a property we're looking for, is a Circumscribed Design always prefered over a Face Centered Design?
We care about many properties, not just rotatability. Often, practical issues affect design choice, like the allowable range of variables. For circumscribed design, the "star" points use larger variable ranges.
Top man
Thank you!
wow, great explanation. can I know a big difference between CCD and BBD?
Thank you for sharing this video. It's answered a lot of questions for me. You said the centre points are repeated in order to detect shifts. How exactly do we determine if there is a shift?
look at your center points raw data and evaluate the noise (Standard deviation or CV) or look for the Pure error term in your DOE analysis in Mintab or whatever software you use. Pure error is the error obtained from repeated measurements such as your center points.
or do you mean shifts from non-linearity?
I’d think you’d need an already prepared control chart in place to check that the centre points (4 say) were between the control limits. You couldn’t detect a shift (step change or trend) from just 4 points alone. However, the 4 points can be used to calculate uncertainty of the effect values (what you’d call partial replication as only one of the runs/treatment combinations is replicated) and you’d want the variation of the 4 points to be smaller than the variation between the levels for each factor otherwise the factor effects are unlikely to be significant. That’s my best guess at an answer.
Thank u sir
Thank you for sharing this video. It's answered a lot of questions for me. You said the centre points are repeated in order to detect shifts. How exactly do we determine if there is a shift?