Quick Answer
Calculate Statistical Process Control Robustness Index
Calculator
Result Interpretation
Statistical Process Control Robustness Index Calculator computes Statistical Robustness Index in dimensionless using the defined engineering formula and the input values provided.
Worked Example
Verified calculation
Given:
- Process Skewness = 0
- Target Cpk = 1.33
- Subgroup Sample Size = 5
- Observed Cpk = 1.33
- Cpk Tolerance = 0.15
- Excess Kurtosis = 0
- Baseline Robustness Factor = 0.2
Expected Result:
- Statistical Robustness Index = 1.0786938680575
Engineering Interpretation:
Under the given input conditions, the calculated result is: Statistical Robustness Index = 1.0786938680575 dimensionless.
The actual numerical result is computed by the Runtime engine using the persisted tool definition. The values shown here come from automatically validated test cases.
Formula / Method
statistical robustness index = (1.0 / (1.0 + pow(abs(process skewness), 1.5) * pow(excess kurtosis, 0.75))) * exp(-0.5 * pow((target cpk - observed cpk) / cpk tolerance, 2)) * (1.0 + (baseline robustness factor * (1.0 - exp(-0.1 * subgroup sample size))))Formula family: formula_quality_spc_robustness_checker
Variables
| Symbol | Label | Role | Description |
|---|---|---|---|
| skewness | Process Skewness | INPUT | Process Skewness |
| kurtosis_excess | Excess Kurtosis | INPUT | Excess Kurtosis |
| cpk_target | Target Cpk | INPUT | Target Cpk |
| cpk_observed | Observed Cpk | INPUT | Observed Cpk |
| cpk_tolerance | Cpk Tolerance | INPUT | Cpk Tolerance |
| sample_size | Subgroup Sample Size | INPUT | Subgroup Sample Size |
| robustness_baseline | Baseline Robustness Factor | INPUT | Baseline Robustness Factor |
| statistical_robustness_index | Statistical Robustness Index | OUTPUT | Statistical Robustness Index |
Calculation Steps
- Enter the process skewness in dimensionless.
- Enter the excess kurtosis in dimensionless.
- Enter the target cpk in dimensionless.
- Enter the observed cpk in dimensionless.
- Enter the cpk tolerance in dimensionless.
- Enter the subgroup sample size in dimensionless.
- Enter the baseline robustness factor in dimensionless.
- Step 1: Compute statistical robustness index.
- Read the statistical robustness index (dimensionless) from the results.
Engineering Summary
Calculate Statistical Process Control Robustness Index
Frequently Asked Questions
What does this calculator calculate?
The Statistical Process Control Robustness Index Calculator estimates Statistical Robustness Index based on the input parameters you provide
Why is process skewness important in this calculation?
process skewness is directly proportional to statistical robustness index. When you enter process skewness in dimensionless, the calculator uses it in the engineering formula to compute the output
How should I interpret the result statistical robustness index?
The calculator outputs statistical robustness index in dimensionless. The result is computed directly from the input values using the defined engineering formula
What units should I use for the inputs?
Enter each value in the units shown next to the input field: Process Skewness (dimensionless), Excess Kurtosis (dimensionless), Target Cpk (dimensionless), Observed Cpk (dimensionless), Cpk Tolerance (dimensionless), Subgroup Sample Size (dimensionless), Baseline Robustness Factor (dimensionless). Make sure all inputs use the specified units for consistent results
What assumptions does this calculator use?
This calculator uses automatically validated engineering formulas. Results are approximate and should be validated against site-specific conditions, applicable codes, and professional engineering judgment
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