Lesson 3 of 5
Reading trends
11 min
Listen to this lesson
A single status report is a photograph. Trends are the film, and they are what lets a test lead forecast whether exit criteria will be met before the date arrives. The most informative trends in SAP testing are the defect arrival and closure curves, the open defect backlog, retest and reopen rates, and the execution burn-down.
Arrival and closure
Plot two lines per day or week: defects raised and defects closed (fixed, retested and confirmed). Early in a cycle, arrivals outrun closures as testers explore and developers catch up. As the cycle matures, arrivals should fall and closures should overtake them. The point where the cumulative closed line converges with the cumulative raised line, and the gap (the open backlog) is shrinking, is the strongest sign that the system is stabilizing.
Severity mix matters more than totals
A falling total can hide a rising number of critical defects. Plot arrivals and the open backlog by severity, at least critical and high separately from the rest. At Contoso, the total open count fell from 140 to 90 in a week, but open critical defects rose from 2 to 5, all in record to report. The total looked like progress; the severity view showed a new problem area.
Retest and reopen rates
The reopen rate is the share of fixed defects that fail retest and are reopened. A healthy rate is low; a rising one means fixes are rushed, not unit-tested, or transported incompletely. It also slows convergence, because each reopened defect re-enters the backlog. Track the age of open critical and high defects too: an aging critical defect is often waiting on a decision, not a developer.
Forecasting exit criteria
Exit criteria usually include something like "no open critical defects, no more than five open high defects with agreed workarounds, all high risks covered". Trends let you forecast whether you will get there. A simple method:
- Take the current open critical and high defects.
- Estimate the net closure rate per day from the last week (closures minus new arrivals of that severity).
- Divide the open count above the threshold by the net closure rate to estimate days to reach it.
- Compare with the days left, and adjust for retest capacity and the reopen rate.
- State the forecast with its assumptions: "If the net closure rate of 1.5 high defects per day holds, we reach the threshold in 6 days; 8 remain."
- Is the open backlog of critical and high defects shrinking?Yes → check rate vs days left · No → escalate: fix capacity, scope or date
- Will the net closure rate reach the exit threshold before the date?Yes → check reopen rate · No → report red with the gap and options
- Is the reopen rate low and stable?Yes → forecast credible; report green or amber · No → address fix quality before trusting the forecast
What would you do?
In Contoso's final cycle, arrivals have dropped sharply for three days and the open backlog is flat. Priya notices that executed tests per day also dropped by half, because finance key users were pulled into training. How should she read the trend?
The execution burn-down
Defect trends tell you about quality; the execution burn-down tells you whether the testing itself will finish. Plot the remaining planned tests per day against an ideal line that reaches zero on the last day of the cycle. A burn-down that flattens usually means blocked tests: missing test data, a broken interface, an unavailable key user or a defect that stops a whole chain. The fix is rarely "test faster"; it is removing the blocker. Count blocked tests separately and name the blocker in the daily view, because one missing intercompany data set can block twenty tests at once.
- Plot defect arrivals and closures; a shrinking open backlog signals convergence.
- Watch severity mix: totals can fall while critical defects rise.
- Track reopen rate and the age of critical and high defects.
- Forecast exit criteria from the net closure rate and state the assumptions.
- Always read defect trends alongside execution volume.
Check your understanding · not graded
Lesson check
1. What most strongly signals that a system is stabilizing?
2. Why plot defects by severity?
3. What does a rising reopen rate usually indicate?
4. Arrivals dropped because execution halved. What is the right interpretation?