Topic 9 - SQC Flashcards
Descriptive Statistics
Describe the quality characteristics; this includes Mean, Standard deviation (SD), range and measure of distribution of data.
Acceptance Sampling
Randomly inspecting a sample of goods and deciding whether to accept the entire lot based on the results.
Statistical process control
Inspecting a random sample to decide whether the product characteristics are within the certain acceptable bounds (process capability and control charts)
What are the phases of quality contol?
1) Acceptance sampling
2) Statistical process control
3) Continuous improvement and Six Sigma
Random Variation
Natural variations in the output of process, created by countless minor factors.
Assignable variation
A variation whose source cay be identified and eliminated.
Variables
to monitor characteristics that can be measured and have a continuum of values, such as height, weight, or volume.
Attributes
to monitor characteristics that have discrete values and can be counted.
X-Bar Chart
All samples are in control
R Chart
One sample is out of control
P-Chart
to monitor the proportion of defective in a process.
What are the nonrandom patterns in control charts
1) Trend
2) Cycles
3) Bias
4) Level Shift
5) Too much Dispersion
Trend
Sustained upward or downward movements
Cycle
Wave patterns
Bias
Too many observations on one side of the centre line
