qc chart 101
TRANSCRIPT
Making a QC Chart
Step 1: Compute the Mean
• With the following data compute for the mean/average
– 1, 3, 5, 7, 9
– 1+3+5+7+9 = 25; 25/5 = 5 = Mean
Step 2: Compute for the Standard Deviation
• SD formula:
Step 2: Compute for the Standard Deviation
• 2.1: Compute for the (X-Mean)
• Data 1, 3, 5, 7, 9; Mean = 5
• 1-5 = -4
• 3-5 = -2
• 5-5 = 0
• 7-5 = 2
• 9-5 = 4
Step 2: Compute for the Standard Deviation
• 2.2: Compute for the (X-Mean)^2
• Data 1, 3, 5, 7, 9; Mean = 5
• 1-5 = -4 = -4^2 or -4 x -4 = 16
• 3-5 = -2 = -2^2 or -2 x -2 = 4
• 5-5 = 0 = 0^2 or 0 x 0 = 0
• 7-5 = 2 = 2^2 or 2 x 2 = 4
• 9-5 = 4 = 4^2 or 4 x 4 = 16
Step 2: Compute for the Standard Deviation
• 2.3: Compute for the S (X-Mean)^2
• Data 1, 3, 5, 7, 9; Mean = 5
• 1-5 = -4 = -4^2 or -4 x -4 = 16
• 3-5 = -2 = -2^2 or -2 x -2 = 4
• 5-5 = 0 = 0^2 or 0 x 0 = 0
• 7-5 = 2 = 2^2 or 2 x 2 = 4
• 9-5 = 4 = 4^2 or 4 x 4 = 16
• Summation = 16 + 4 + 0 + 4 + 16 = 40
Step 2: Compute for the Standard Deviation
• 2.4: Compute S (X-Mean)^2 / n-1
• Data 1, 3, 5, 7, 9; Mean = 5
• Summation = 16 + 4 + 0 + 4 + 16 = 40
• 40 / (5-1)
• 40 / 4
• 10
Step 2: Compute for the Standard Deviation
• 2.5: Compute SD
• Data 1, 3, 5, 7, 9; Mean = 5
• Summation = 16 + 4 + 0 + 4 + 16 = 40
• Sqrt 10
• SD = 3.16
Step 3: Compute 1SD 2SD 3SD Intervals
• Data 1, 3, 5, 7, 9; Mean = 5
• Summation = 16 + 4 + 0 + 4 + 16 = 40
• SD = 3.16
SD Range ComputationMean+(xSD)
Result
+3SD 5 + (3.16x3) 14.48
+2SD 5 + (3.16x2) 11.32
+1SD 5 + (3.16x1) 8.16
Mean 5 + (3.16x0) 5
-1SD 5 - (3.16x1) 1.84
-2SD 5 - (3.16x2) -1.32
-3SD 5 - (3.16x3) -4.48
Step 4: Construct a Chart and Plot the Data
• Data 1, 3, 5, 7, 9; Mean = 5
• Summation = 16 + 4 + 0 + 4 + 16 = 40
• SD = 3.16
-4.48
-1.32
1.84
5
8.16
11.32
14.48
+3SD 14.48
+2SD 11.32
+1SD 8.16
Mean 5
-1SD 1.84
-2SD -1.32
-3SD -4.48
Step 5: Interpret the Chart Using Wesgard Rule
-4.48
-1.32
1.84
5
8.16
11.32
14.48