Split-Plot Response Info Upfront Power

Responses are the quality characteristics being measured at each run in the experiment. These must be numeric, and the values must be sensitive enough to reflect changes in the process or product as the run conditions are changing.

Responses: The number of responses being measured.

Edit Model: The default power model is for all possible main effects, click here to change that setting.

Variance ratio: The ratio of the whole plot variance to the subplot variance. A value of 1 is a balanced starting point that will work for most cases.

Response Information

Name: A descriptive name for the response.

Units: The units of measure for the response.

Response Type: Choose Continuous or Proportion.

Continuous is used for a standard measured response.

Proportion is used when the response is similar to fraction defective.

Diff. to Detect (Difference to Detect) or Delta “Signal” is the minimum change in the response considered large enough to be a practical change. It is the minimum amount of change you want the design to detect as significant. A larger change is easier to detect resulting in higher power.

Est. Std. Dev. (Estimated Standard Deviation) or Sigma “Noise” is an estimate for the run to run standard deviation of the response. The estimate can come from a pilot study, a similar process, scientific knowledge and as a last resort – guess.

The Delta/Sigma “Signal/Noise” ratio is used to determine the probability of detecting an effect.

The default “Signal” of 2 and “Noise” of 1 are a common setting for checking power. Leaving these as is will estimate the power for a 2 standard deviation effect. Change these values to something more realistic to get a better estimate of power for the experiment.

For split-plot designs, the run to run variation (noise) is associated with the subplot runs within groups.

Press the Next button to calculate power and/or move on through the build.

Clicking the Next button without entering anything, a single response named “R1” with no units of measure will be created. It is recommended that names and units of measure be entered for each response.