Why are DOE simulated values negative?

[#1]

I am struggling to find the reason of getting the negative numbers which comes from simulation in DOE. The input dataset has seven Cost Type variables (X) and response variable is Total Cost (Y). I have imputed the data in custom design (see screenshot “DEO Setup_1”). The Min and Max values of the variables are as follows.

	Min	Max
Cost Type 1	11.31	18.91
Cost Type 2	8.2	16.39
Cost Type 3	8.3	17.88
Cost Type 4	8.08	17.87
Cost Type 5	9.79	18.12
Cost Type 6	7.41	18
Cost Type 7	10.99	18.95
Total Cost	64.08	126.12

In the simulated data file (attached), I expected to see the data under Total Cost should be in between 64.08 (Min) and 126.12 (Max). However, it is actually in between -5.201 (Min) and 126.12 (Max).

Can anybody suggest why is this and how to get the simulated values in between 64.08 (Min) and 126.12 (Max)?

[#2]

The simulated data have nothing to do with the original Total Cost data. The simulated data depends entirely on your definition of the model parameters. Here are the definitions you used:

I would expect the simulated data based on your definitions.

[#3]

Thank you @Mark_Bailey OK. Why are some  Total Cost Data negative? I expected that they should between 64.08 (Min) and 126.12 (Max). These are the values I added in designing the DOE.

[#4]

Hi @Mark_Bailey 

I can deal with the simulated cost (see attached). However, why are some  Total Cost Data negative? I expected that they should between 64.08 (Min) and 126.12 (Max). These are the values I added in designing the DOE.

[#5]

Why would you expect the simulated Total Cost values to be between 64.08 and 126.12? The simulation parameters determine the simulated values in the data table column.

You entered those values in the definition of the response. They are saved as the Response Limits column property. The simulator does not use those values. The Prediction Profiler uses those values when you optimize the response using the fitted model. They represent the range of outcomes that are acceptable to you. You defined this Total Cost to minimize it. So if you achieve a response of 64.08 or lower, the desirability equals 1. If you achieve a response of 126.12 or higher, the desirability is 0. The desirability is between 0 and 1 when the response is between those two values. That is what your definition means.

[#6]

Have you read the chapter on Custom DOE in the JMP Design of Experiments Guide? It explains the design parameters and how to use them.