ITPEC IP October 2020 Question 53
Which of the following is a diagram where bugs detected during the testing of a system are accumulated by their cause and arranged in the order of higher frequency of cause, and a cumulative curve is inserted?
Explanation
Pareto chart — bug counts per cause drawn as bars in descending order, with a cumulative curve over them.
A Pareto chart draws one bar per category, largest first, and a line of the cumulative percentage. Usually a few causes account for most of the bugs: where the cumulative curve rises steeply are the causes whose removal eliminates the most bugs, so they are dealt with first. The same chart is used in ABC analysis.
Answer (c)
Why not others:
- •(a) Scatter diagram — plots pairs of two quantities as points to show whether they are correlated; it has no categories and no cumulative curve
- •(b) Cause and effect diagram — the fishbone diagram arranges the possible causes of one effect in branches; it shows no counts, so it cannot rank them
- •(d) Histogram — bars of how many values fall in each interval of one numeric quantity, kept in the order of the intervals rather than sorted by frequency, and with no cumulative curve
Key rule: Sorted bars plus a cumulative line is a Pareto chart, used to decide what to tackle first; a histogram shows the shape of a distribution, a scatter diagram a correlation, a fishbone diagram the possible causes.
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