There are 14 different defects that can occur on a completed time card. The payroll department collects 328 cards and finds a total of 87 defects. DPU =

Defects-per-unit (DPU) is defined as the total number of defects observed divided by the total number of units inspected. In this case the payroll department found 87 defects in 328 time-card units; therefore DPU = 87 ÷ 328 = 0.265 (rounded)

B. Uses total opportunities (units × defect types); that calculates DPO, not DPU.
C. Inverts the definition; compares possible defect types to total defects.
D. Divides defects by types, giving average defects per type, not per unit.
E. Inverts the required ratio; gives units per defect, not defects per unit.
F. Multiplies by 1 000 000 and divides by opportunities; that is defects-per-million-opportunities (DPMO).

1. T. Kubiak & D. Benbow

The Certified Six Sigma Black Belt Handbook

3rd ed.

ASQ Quality Press

2017

Chap. 9

“Defect Metrics

” p. 487: “DPU = total defects ÷ total units.”

2. MIT OpenCourseWare

15.075J Statistical Thinking & Data Analysis

Lecture 18 notes

Section “Yield Metrics

” p. 3: “Defects per unit (DPU) = number of defects / number of units inspected.”

3. G. Eckes

Six Sigma for Everyone

Wiley

2003

Chap. 4

p. 67: formula and example illustrating DPU calculation identical to option A.