1.
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Select DOE > Custom Design.
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2.
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In the Factors outline, type 3 next to Add N Factors.
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3.
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Click Add Factor > Continuous.
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4.
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Click Add Factor > Blocking > 3 runs per block.
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The blocking factor X4 shows only one level under Values. This is because the run size is unknown at this point.
Figure 5.21 Factors Outline Showing One Block for X4
5.
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Click Continue.
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Figure 5.22 Factors Outline Showing Three Blocks for X4
The Factors outline now shows an appropriate number of blocks, calculated as the Default run size divided by the number of runs per block. For this example, the default sample size of 9 requires three blocks. The Factors outline now shows that X4 has three values, indicating the three blocks.
6.
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7.
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In the Model outline, click Interactions > 2nd.
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Figure 5.23 Factors Outline Showing Six Blocks for X4
The Number of Runs panel now shows that 18 is the Default run size. The Factors outline now shows six values for X4, indicating six blocks.
Note: Setting the Random Seed in step 8 and Number of Starts in step 9 reproduces the exact results shown in this example. In constructing a design on your own, these steps are not necessary.
8.
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(Optional) From the Custom Design red triangle menu, select Set Random Seed, type 458027747, and click OK.
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9.
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(Optional) From the Custom Design red triangle menu, select Number of Starts, type 10, and click OK.
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10.
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Click Make Design.
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Figure 5.24 Fixed Block Design
In the design, look at the blocking factor, X4. The six blocks are represented. When you conduct your experiment, each day you will run three trials, where X4 = 1 on the first day, X4 = 2 on the second day, and so on. So you want the design table to randomize the trials within blocks. In the Output Options panel, the Randomize within Blocks option is already selected for Run Order.
11.
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Click Make Table.
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Figure 5.25 Design Table for Fixed Block Design