Sigma Siege

SC Quality Guild arcade

Score0

Sigma level1σ

Escapes left3

Hold the line

Defects are descending on the process. Shoot them down before they cross the lower control limit. Clear a wave to raise your sigma level. Reach six sigma to win.

σVariation, 30 points ∩Bell curve, 20 points ⌃Out-of-control point, 15 points ✕Defect, 10 points ★Special cause, 50 to 300 points

Keyboard: arrow keys or A and D to move, Space to fire, P to pause. On a phone, use the buttons or drag on the screen. The bars near the bottom are your specification limits: they absorb hits and wear away.

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The board resets at midnight Eastern time. Only your initials are posted.

The quality behind the game

The dashed lines at the top and bottom of the screen are control limits. A process in control keeps its points between them. When a defect crosses the lower control limit, it has escaped to the customer, which is why you lose a life.

Each wave you clear raises your sigma level. The defects-per-million figures shown between waves are the standard Six Sigma conversion, which allows for a 1.5 sigma long-term shift: 66,807 at three sigma, 6,210 at four, 233 at five and 3.4 at six.

The red star is a special cause: an unusual event outside the normal pattern of variation. It is worth chasing down, and it is worth the most points.

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