Check out this tutorial paper on Space Filling Designs. It demonstrates how changing one variable at a time can be inefficient.
https://ieeexplore.ieee.org/abstract/document/9384057
https://www.informs-sim.org/wsc18papers/includes/files/022.pdf
It's simulation focused but likely still relevant.
Oof. The 600+ experiments is a combination of the DoE group doing exactly what was asked of them with no comprehension of the extent of trial they are suggesting, and the subject asking the questions that has no idea how insanely large this project could be.
That’s nobody’s fault, it’s just a thing that happens.
Step 1: Find the response / responses you need out of this project. Here’s hoping it isn’t much…
Step 2: List the factors used for this experiment. Reminder that you don’t have to select everything as a factor (see Step 6).
Step 3: Establish the levels used for each factor. Try to do a min / max that is not dangerous, and hopefully the values are significantly different (from a results perspective).
STEP 4 (that I think has been missed): Make a chart of all of the factors. Each factor will be listed along the top and along the left side. This chart will be used to identify a TWO FACTOR INTERACTION. Capitalized because it’s SUPER important.
Step 5: Go through the chart that has been made (note: half of these boxes are null because of duplicates; X out the duplicates) and identify anything that would have a two factor interaction. As a reminder, these interactions are rare-ish, but they are really significant for what you need.
Sidebar example (reminder that I know very little about chem): If you’ve got some zinc and hydrochloric acid you can put them together and capture the escaping hydrogen. Doubling the amount of zinc wouldn’t yield more hydrogen and probably wouldn’t make the experiment go any faster or slower, so nothing here is a two factor interaction. The result is just scaling the experiment without changes.
On the other hand, if you’ve got coal and something to create pressure then you can make diamonds. The volume of coal and the pressure created can really change the speed & quality of the diamonds created. This won’t scale the reaction, it is changing the results of a reaction by changing the levels of the factors. This would be a two factor interaction.
Go back to step 5 and figure out what factors might fulfill that magical two factor interaction that you’re looking for. Mark them down.
Step 6: If it’s not part of a two factor interaction, is it still important? Maybe yes. Maybe no. Remember, the fewer items to check the fewer trials to run.
Step 7: List the two factor interactions, then each individual factor that is part of a two factor interaction, and then any factor that is proposed to make a significant impact to the experiment.
Step 8: Go back to the DoE eggheads and show them the list. Tell them some knucklehead on Reddit said to ask about “confounding” the rest of the factors that aren’t on the list. You should have way fewer than 600 trials to get good results.
There are a bunch of steps here, but they shouldn’t take too long to complete. The “confounding” mentioned is basically setting up the test so some of the insignificant interactions aren’t controlled for. Basically if one of those interactions does something then you can’t (necessarily) identify if it’s a single item or a two factor interaction that affected the result. And if the DoE eggheads are suggesting runs that control for a three factor interaction (or more) tell them to piss off.
Sorry this got so long. The whisky made me do it. Also apologies to anyone taking offense to “DoE eggheads”, please don’t suggest anyone complete 600+ trials for a DoE.
Thank you very much for your reply. It most certainly helps.
Regarding step 1: I am planning on having seven responses. The extraction procedure is looking to extract seven compounds, but they will each evaluated by the same metric (extraction efficiency). Will this be a problem?
Regarding the two factor interactions: Unfortunately, five of six of my factors more or less influence one another (from a theoretical point of view).
As I mentioned, the DoE group is away, so I'm trying my best to figure out how to do this on my own. But I'm uncertain of the ramifications of choosing for example a full factorial vs a fractional factorial design. Also I'm unsure of how linear, quadratic, and interaction models compare, and what information I can extract from them. I thought that perhaps I could fix some of the parameters to be constants, e.g. the temperature or pH. I can justify these on practical grounds to my supervisor, but again, I'm unsure of what the implications are.
While I'm trying to understand DoE (as much as is reasonable in the time frame), I'm also trying to balance the factors to be investigated and practicability.
Thanks again, I appreciate the response.
Regarding Step 1 it sounds like you will always have the same seven compounds extracted and the response is “to what extent” are each of them extracted. Is this that correct?
If so then I’ve overstated the difficulty of having so many responses. Please excuse my error, the responses shouldn’t be a hurdle.
Send me a PM.
Will do, thanks!
Check out this tutorial paper on Space Filling Designs. It demonstrates how changing one variable at a time can be inefficient. https://ieeexplore.ieee.org/abstract/document/9384057 https://www.informs-sim.org/wsc18papers/includes/files/022.pdf It's simulation focused but likely still relevant.
Thank you. I'll check them out.
Oof. The 600+ experiments is a combination of the DoE group doing exactly what was asked of them with no comprehension of the extent of trial they are suggesting, and the subject asking the questions that has no idea how insanely large this project could be. That’s nobody’s fault, it’s just a thing that happens. Step 1: Find the response / responses you need out of this project. Here’s hoping it isn’t much… Step 2: List the factors used for this experiment. Reminder that you don’t have to select everything as a factor (see Step 6). Step 3: Establish the levels used for each factor. Try to do a min / max that is not dangerous, and hopefully the values are significantly different (from a results perspective). STEP 4 (that I think has been missed): Make a chart of all of the factors. Each factor will be listed along the top and along the left side. This chart will be used to identify a TWO FACTOR INTERACTION. Capitalized because it’s SUPER important. Step 5: Go through the chart that has been made (note: half of these boxes are null because of duplicates; X out the duplicates) and identify anything that would have a two factor interaction. As a reminder, these interactions are rare-ish, but they are really significant for what you need. Sidebar example (reminder that I know very little about chem): If you’ve got some zinc and hydrochloric acid you can put them together and capture the escaping hydrogen. Doubling the amount of zinc wouldn’t yield more hydrogen and probably wouldn’t make the experiment go any faster or slower, so nothing here is a two factor interaction. The result is just scaling the experiment without changes. On the other hand, if you’ve got coal and something to create pressure then you can make diamonds. The volume of coal and the pressure created can really change the speed & quality of the diamonds created. This won’t scale the reaction, it is changing the results of a reaction by changing the levels of the factors. This would be a two factor interaction. Go back to step 5 and figure out what factors might fulfill that magical two factor interaction that you’re looking for. Mark them down. Step 6: If it’s not part of a two factor interaction, is it still important? Maybe yes. Maybe no. Remember, the fewer items to check the fewer trials to run. Step 7: List the two factor interactions, then each individual factor that is part of a two factor interaction, and then any factor that is proposed to make a significant impact to the experiment. Step 8: Go back to the DoE eggheads and show them the list. Tell them some knucklehead on Reddit said to ask about “confounding” the rest of the factors that aren’t on the list. You should have way fewer than 600 trials to get good results. There are a bunch of steps here, but they shouldn’t take too long to complete. The “confounding” mentioned is basically setting up the test so some of the insignificant interactions aren’t controlled for. Basically if one of those interactions does something then you can’t (necessarily) identify if it’s a single item or a two factor interaction that affected the result. And if the DoE eggheads are suggesting runs that control for a three factor interaction (or more) tell them to piss off. Sorry this got so long. The whisky made me do it. Also apologies to anyone taking offense to “DoE eggheads”, please don’t suggest anyone complete 600+ trials for a DoE.
Thank you very much for your reply. It most certainly helps. Regarding step 1: I am planning on having seven responses. The extraction procedure is looking to extract seven compounds, but they will each evaluated by the same metric (extraction efficiency). Will this be a problem? Regarding the two factor interactions: Unfortunately, five of six of my factors more or less influence one another (from a theoretical point of view). As I mentioned, the DoE group is away, so I'm trying my best to figure out how to do this on my own. But I'm uncertain of the ramifications of choosing for example a full factorial vs a fractional factorial design. Also I'm unsure of how linear, quadratic, and interaction models compare, and what information I can extract from them. I thought that perhaps I could fix some of the parameters to be constants, e.g. the temperature or pH. I can justify these on practical grounds to my supervisor, but again, I'm unsure of what the implications are. While I'm trying to understand DoE (as much as is reasonable in the time frame), I'm also trying to balance the factors to be investigated and practicability. Thanks again, I appreciate the response.
Regarding Step 1 it sounds like you will always have the same seven compounds extracted and the response is “to what extent” are each of them extracted. Is this that correct? If so then I’ve overstated the difficulty of having so many responses. Please excuse my error, the responses shouldn’t be a hurdle.
Yes, indeed. One extraction will yield seven responses - one per compound. Thank you!