For each of the following scenarios, explain which control chart you would choos
ID: 3840002 • Letter: F
Question
For each of the following scenarios, explain which control chart you would choose to verify if the process is under statistical control.
Scenario 1:
Company “Acme” ships regular monthly releases of their software product. They decide to take a simple approach to check their productivity. They measure lines of code produced per day worked during 5 consecutive releases.
Scenario 2:
An Agile team runs on weekly sprints. An automated set of test cases intended to verify that the product is stable is run every night and produces several bugs based on a daily build of a software product. This process runs regularly for 4 months and is part of the team’s quality control processes. The team wishes to know how much churn (number of defects) the weekly sprints are causing in the main product with the added work per sprint.
Scenario 3:
Company “Supersoft” produces a product that that is compiled on a regular basis. Recently, the team leader receives a complaint from one of the team members that builds are taking too long to compile. That value (time to build) can be measured daily and the team wishes to understand if the variations being experienced are within normal rates or not.
Explanation / Answer
Scenario 1:
Use p & np charts. As,
P & np charts
For discrete-attribute data, p-charts and np-charts are ideal. Attribute data is for measures that categorize or bucket items, so that a proportion of items in a certain category can be calculated. Thus a p-chart is used when a control chart of these proportions is desired.
An np-chart is appropriate when the number of items used to calculate each proportion is the same. For example, 100 reports may be reviewed each week and categorized as either accurate or inaccurate. The proportion of inaccurate reports could be plotted on a p-chart or the actual number of inaccurate reports could be plotted on an np-chart. If the number of reports reviewed each week varies, then a p-chart must be used.
Scenario 2:
Use p & np charts. As,
P & np charts
For discrete-attribute data, p-charts and np-charts are ideal. Attribute data is for measures that categorize or bucket items, so that a proportion of items in a certain category can be calculated. Thus a p-chart is used when a control chart of these proportions is desired.
An np-chart is appropriate when the number of items used to calculate each proportion is the same.
Scenario 3:
Use C & u chart
As, Discrete-count data differs from attribute data in that the occurrence of a characteristic or event can be counted, but a non-occurrence can not be counted. Thus the data plotted for a c-chart or u-chart is always the count of occurrences. The c-chart is used when the opportunity for occurrences is equal for each data point and the u-chart is required when the opportunities differ.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.