# mixture-amounts experiment

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• #37662

Lily
Participant

This is come from Minitab help about the mixture-amounts experiment”In the simplest mixture experiment, the response is assumed to only depend on the proportions of the components in the mixture. In the mixture-amounts experiment, the response is assumed to depend on the proportions of the components and the amount of the mixture. For example, the amount applied and the proportions of the ingredients of a plant food may affect the growth of a house plant. When a mixture experiment is performed at two or more levels of the total mixture amount, it is called a mixture-amounts experiment”.
What is it meaning? can someone paste a sample about it?
Thanks!

0
#111294

migs
Participant

Example, if you have 2 factors, Fertilizer A and B and you want to experiment on the effect on plant growth. Also Low and High Levels for A is 10 and 100 grams while B is 50 and 80 grams.
If we simply use the full factorial (say 2-levels each), we come up with:
Run       A
1
2
3
4

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#111295

migs
Participant

Example, if you have 2 factors, Fertilizer A and B and you want to experiment on the effect on plant growth. Also Low and High Levels for A is 10 and 100 grams while B is 50 and 80 grams.
If we simply use the full factorial (say 2-levels each), we come up with:
Run       A       B      Total Fertilizer
1          10      50       60
2          10       80      90
3          100     50      150
4           100    80       180
Notice that the total fertilizer used for each run varies, which might affect the response of the experiment. In mixture experiments, experiments are designed in such a way that the Total amount per experimental run is constant.

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#111300

Lily
Participant

Hi:
Thanks very much!
Can you tell me how should we operate it in Minitab 14? whar should we fill in the SStat > DOE > Mixture > Create Mixture Design > Component both in Multiple totals (up to 5) and lower/upper for factors?
Tks!

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#111327

Lily
Participant

Hi Mings:
Thanks very much!
Can you tell me how should we operate it in Minitab 14? whar should we fill in the SStat > DOE > Mixture > Create Mixture Design > Component both in Multiple totals (up to 5) and lower/upper for factors?
Tks!

0
#111328

Tim F
Member

The space for “Multiple totals” is how much total amount of mixture you want. In the fertilizer example, if you typed in “50 100 200” then Minitab would produce sets of experiments where the total amount of all the fertilizers put together were either 50, 100 or 200. The space for Lower/upper lower limit puts limits on the amount of each component. This is always relative to the first number in the “multiple totals” section. So if you type 20 and 40 for component A, then out of 50 total, component A would always be between 20 and 40 (i.e. 40% to 80%). Out of 100, it would be 40 to 80 (i.e. still 40% to 80%).Note that when you limit the amounts of certain components, then you limit which types of designs you can run.Tim F

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