CQIA Statistical Methods 3

Question 1

What is the purpose of stratification in data analysis?

Accepted Answer

To separate data into subgroups to identify patterns

Answer

Stratification divides data into meaningful subgroups (by shift, machine, operator) to reveal hidden patterns.

Question 2

An X-bar chart is used to monitor which characteristic of a process?

Accepted Answer

The average (mean) of subgroup measurements

Answer

An X-bar chart tracks the subgroup average over time to detect shifts in process centering.

Question 3

Which statistical tool displays the frequency distribution of continuous data?

Accepted Answer

Histogram

Answer

A histogram displays how continuous data is distributed across intervals (bins), showing shape and spread.

Question 4

The interquartile range (IQR) is calculated as:

Accepted Answer

Third quartile minus first quartile

Answer

IQR = Q3 − Q1, representing the spread of the middle 50% of data and is resistant to outliers.

Question 5

A c-chart is most appropriate when:

Accepted Answer

Counting defects per unit with constant sample size

Answer

The c-chart monitors the count of defects per unit when the opportunity for defects is constant.

(CQIA) ASQ Certified Quality Improvement Associate Practice Test