Overview
This is a trend chart showing the rate of defects arrival and closure (fixing) over the project duration. Use this
chart to ensure that arrival and closure rates have some correlation (in other words, that your arrivals do not
consistently outpace your closure, resulting in a high defect backlog). You can also use this chart to determine the
remaining defect backlog, and to project the future defect arrival and close rate up to and including the post-ship
phase.
Measurement Method
Count
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Number of defects found and closed each unit of time (usually a week, but could be a day or month, depending on
your iteration length). This is a graph over time, typically in two lines.
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You can also superimpose bars of
remaining defects over the line graphs, because this may not
always be evident. (The close rate can exceed the arrival rate for one or more data points, which can
obscure the backlog.)
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Total cumulative defects found and closed. This is a graph over time, typically in two lines. In this case, the
difference between the two lines shows the defects remaining (not including any backlog that predates the
collection of arrivals.)
Measurement Analysis
As the end of cycle (ship date) nears, you should expect to see the arrival rate slowing and the closure rate
surpassing it. This indicates that fewer defects are being found (hopefully because you have found them already), and
that any backlog or outstanding defects are being fixed. If the arrival curve does not taper down, it suggests that you
may continue to find defects post-ship. In the cumulative chart, you expect to see the gap between total
found and total fixed . If a large gap remains, you have many defects that are still not closed:
this may necessitate lengthening the schedul,e or shipping with unclosed defects.
Note that looking purely at arrivals and closures does not include defects in a backlog that predates the data
collection.
Use this metrics in conjunction with Defect Density at Customer Ship
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