To define a custom mixture designmain topic see also
To define a custom mixture design1 Choose Stat > DOE > Mixture > Define Custom Mixture Design.
2 In Components, enter the columns that contain the component data. Data must be in the form of amounts. (When the mixture total is one, amounts and proportions are equivalent.
3 If you have process variables in your design, enter the columns in Process variables.
4 If you have an amount variable, under Mixture Amount, choose In column, and enter the column that contains the amount data.
5 Click Lower/Upper.
6 If you have an mixture-amounts experiment, Minitab will enter the smallest value in your amount column in Total value matching Lower/Upper bounds. If this is not the value you want, change it to any other total in your amount column.
7 Minitab will fill in the lower and upper bound table from the worksheet. Make any necessary corrections, then click OK.
8 Do one of the following:
1 If you have a column that contains the standard order of the experiment, under Standard Order Column, choose Specify by column and enter the column containing the standard order.
2 If you have a column that contains the run order of the experiment, under Run Order Column, choose Specify by column and enter the column containing the run order.
3 If you have a column that contains the design point type, under Point Type Column, choose Specify by column and enter the column containing the point types.
4 If your design is blocked, under Blocks, choose Specify by column and enter the column containing the blocks.
5 Click OK in each dialog box.