Practice Test Geeks(SPC) Statistical Process Control Certification Practice Test
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Data Collection & Interpretation Flashcards

7 cards from real SPC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Data Collection & Interpretation flashcards as text

  1. Which formula correctly calculates the mean (Xbar) of a subgroup with values 8, 10, 12, and 14?

    Answer: (8+10+12+14) / 4 = 11

    The subgroup mean is the arithmetic average: sum all values and divide by the count, giving (44)/4 = 11.

  2. A quality team notices that data from one shift consistently shows higher average values. This is BEST addressed by:

    Answer: Stratifying data by shift and investigating the shift-specific cause

    Stratifying by shift isolates the factor causing the difference, enabling root cause analysis and targeted corrective action.

  3. In SPC data collection, a sampling plan that selects every nth unit is called:

    Answer: Systematic sampling

    Systematic sampling selects units at a fixed interval (every nth unit), providing even coverage across production without full randomization.

  4. Which statistic measures the spread of individual measurements within a subgroup on an Xbar-R chart?

    Answer: Range (R)

    The range R = maximum minus minimum within a subgroup measures within-subgroup variation, which is plotted on the R chart.

  5. When a process is described as 'in statistical control,' it means:

    Answer: Only common cause variation is present and the process is stable and predictable

    Statistical control means the process exhibits only inherent (common cause) variation, making future output predictable within control limits.

  6. A quality engineer discovers that measurement data has a uniform distribution rather than the expected bell shape. This may indicate:

    Answer: Data from multiple machines or operators has been pooled without stratification

    A uniform distribution often results from mixing data from several processes or sources, each with different means, which flattens the combined histogram.

  7. Which of the following actions BEST ensures data integrity during SPC data collection?

    Answer: Defining clear operationally defined measurement procedures and training all collectors

    Operational definitions and trained personnel eliminate ambiguity and reduce measurement system variation, ensuring data accurately reflects the process.