For long-term data, ZLT = ZTOTAL, expressed as Zlt-total,
where
is the inverse normal cumulative distribution function, which assumes a right-sided tail.
When displaying long-term metrics, ZLT appears as Zlt-total. This metric is equal to Z-LSL if there is only a lower specification limit or Z-USL if there is only an upper specification limit.
For short-term data, ZLT = ZST - ZScoreShift. When displaying short-term metrics, ZLT appears in the capability metrics table as Zlt.