Statistical Methods Flashcards

When constructing a Pareto chart, defect categories are ordered:

Answer: From most to least frequent

Pareto charts arrange categories from highest to lowest frequency to highlight the vital few contributors.

What does a control chart's upper control limit (UCL) represent?

Answer: Three standard deviations above the process mean

The UCL is set at ±3 standard deviations from the mean, representing the expected range of common cause variation.

A team notices that defect rates differ significantly between the day and night shifts. Which tool would best confirm this finding statistically?

Answer: Histogram comparison or hypothesis test

Comparing histograms by shift or running a hypothesis test quantifies whether the difference is statistically significant.

Which of the following is an example of attribute data?

Answer: Pass/fail inspection result

Attribute data classifies items into categories (pass/fail, defective/not defective) rather than measuring a continuous scale.

The standard deviation of a sampling distribution of means is called the:

Answer: Standard error of the mean

The standard error of the mean equals the population standard deviation divided by the square root of sample size.

Which chart is used when subgroup sizes vary and you want to track the proportion of nonconforming items?

Answer: p-chart

The p-chart accommodates variable subgroup sizes by plotting proportion defective rather than count.

A box plot (box-and-whisker plot) displays which of the following?

Answer: The median, quartiles, and potential outliers

A box plot shows the median (center line), Q1 and Q3 (box edges), and whiskers extending to min/max or outliers.