Reference Interval

Reference interval can be input on step 3 under "Characteristics"

As you can see, there are 3 types of reference intervals. Some results (Cg, Cgk, u_LIN) are always computed with respect to Specification Limits. Q_MS, Q_MP, C_MS, C_MP and Q_ATTR can be computed with respect to any of the three depending on which are available.

1. Process Limits. If filled in, these are always used.
2. Process Capability. In case you have other than usual capability prescribed for this process. This is the index that modifies Specification Limits.
3. Specification Limits. The most basic reference. If none of the above are filled in, Specification Limits are used.