Here's a brief list of terms and abbreviations frequently encountered in statistical readings.

LSL and USL — Lower Specification Limit and Upper Specification Limit (the tolerance range).

L-Out% — The percentage of measurement values falling below the LSL.

H-Out% — The percentage of measurement values falling above the USL.

STD — "Standard deviation," which is a statistical measure of variation and a measure of the spread of data in relation to the mean. STD is the most common measure of the variability of a data set.

6STD — Standard Deviation value multiplied by 6. It represents the width of the normal curve.

Pp — Pp is a Process Performance index which measures the performance of the process. The index compares the variation of the process to the allowable variation set for the specification limits (USL and LSL)

Ppk — The Ppk indicator is a Process Performance index which tells how well the process is centered, or how distant the mean of the process is compared to its specification limit.