Cycle Time Control Chart(2.7.12)

Individual delivered-issue cycle times plotted by delivery date, with the mean and upper / lower control limits (mean plus or minus two standard deviations) computed over every delivered cycle the project has, not over a recent window. The lower limit is shown only where two standard deviations below the mean is above zero; on the right-skewed spread typical of cycle times that bound falls below zero, no cycle could reach it, and the chart shows no lower limit rather than a line at zero. A project with fewer than five delivered cycles is not given control limits: one cycle has no standard deviation at all, and two to four give a spread that moves sharply with the next ticket, so limits drawn there would state a precision the data does not have. Its points carry no signal either: with too little distribution to compare against, they are drawn in gray as unrated, not in blue as if they were in control. Points outside the control limits are statistically unusual and worth investigating. Click a point to open the issue in Jira. Use the date and project filters to focus the view.

When the reference lines appear

Control limits describe one project's distribution, so a single mean or limit cannot be true of several projects at once. The lines are therefore drawn only when the plotted issues all belong to one project — use the project filter to bring them back. With more than one project in view the chart plots the points and omits the three lines.

Nothing is lost by that. Each point is colored against its own project's limits, computed in the data rather than read off the drawn line, so the coral and green points carry the same verdict whether or not a line is on screen. A coral point among several projects means that issue was slow for the project it belongs to.

How this chart works

Scatter plot of individual delivered issues plotted by delivery date (X) and cycle time in days (Y). Issues closed into an abandoned or duplicate status are not plotted and do not move the mean or the control limits. Each delivered issue is one point even if its issue type changed while it was open: the point carries the type the issue holds most recently, identified by its Jira issue-type id, so a renamed type does not split a project's points or move its limits. Where the lines are drawn, they are the mean (solid gray), the upper control limit at two standard deviations above it (dashed coral), and — where that bound exists — the lower control limit (dashed green). Points are colored by their statistical signal: coral above the project's upper limit (statistically slow outliers), green below its lower limit (statistically fast), blue for in-control. Gray marks an unrated point: the project has fewer than five delivered cycles, so there are no limits and no verdict is possible. The comparison is made against the project's own limits rounded to the same two decimals the chart would draw, so a point sitting on a line reads as in-control rather than as an outlier. Where a project has no lower limit, none of its points can be green. When no plotted project has a lower limit, the Below LCL legend entry is left out rather than promising a category no point can reach.

Use the date, project, and issue-type filters to focus. Hover a point for the issue key, cycle days, and signal.