12. Quality Diff and Availability Diff

The Quick Start Guide and Pages and Visualizations in Detail describe how MQC presents the quality of your project through various visualizations in a number of pages. The quality value presented in these pages/visualizations are more or less absolute. In other words, the quality values are calculated based on the data collected for a particular revision.

Quality Diff and Availability Diff introduces another perspective of relative quality in addition to the absolute quality compared against targets. For example, at any point of time, you might be interested if the quality of your project, an artifact or a quality property has improved or deteriorated compared to another revision.

The Diff tiles in the dashboard and the Diff View for pages provides you with the flexibility to view the data in terms of difference relative to a base revision.

12.1. Dashboard

The Dashboard gives you an overview of the entire project at a glance (see Dashboard).

The Diff tiles, “Quality Diff by Artifact” and “Availability Diff By Artifact” are part of the default dashboard layout.

The comparison base drop down in the Diff in Tiles menu of the left-hand side panel allows you to choose between different revisions for calculating the diff against the current revision. As default the comparison base is set to the relative previous revision.


Figure 12.1 Dashboard Diff in Tiles.

The comparison bases in details are as follows:

  • Relative:

    • Previous Revision: With this as base, the difference is calculated for every revision against a revision before it.

    • Previous Milestone: Milestones are special revisions meant to signify the completion of a phase in your project (see Project Milestone Structure). Thus this option will diff every revision against the milestone occurring before it.

  • Fixed:

    Here a list of all revisions is available. The diff for every revision is then calculated against the fixed selected revision.

12.2. Diff Pages

All Quality pages and the Data Availability page have a menu in the left panel which allows you to navigate to the Diff Page of the current page. You can also create the required Diff Pages by selecting it in the Manage Pages dialog.

While on a Diff Page the comparison base for the diff can be selected in the left menu, similar to the dashboard.

Additionally, the Actions menu provides a Show Normal View option to navigate to the original page.


Figure 12.2 Quality HeatMap Diff page.

The Quality HeatMap Diff is one such diff page (see Figure 12.2). Here you can see a visible change in the color scheme and visualization content compared to the normal Quality HeatMap page.


On Diff Pages differences between -10 and 10 are shown with one decimal point in KPIs and in Heatmap.

The color scheme is such that any negative difference is denoted by red, where a lighter shade shows a small negative diff and a darker shade shows a large negative diff. Similarly the positive difference is denoted by lighter to darker shades of green. No improvement or zero diff is denoted by white color.

The KPIs on this page contain the diff values with a + and - sign as a prefix and pp as a postfix. Here pp stands for percentage points. For example, if the quality value at Revision 1 was 80% and the quality value at Revision 2 is 88% then there is a positive diff of +8 pp.

The diff values are sorted from worst negative diff to best positive diff in ascending sort order (see Figure 12.3) and from best positive diff to worst negative in descending sort order (see Figure 12.4). In ASC and DESC sort order 0 pp are at the bottom of the KPI.


Figure 12.3 KPIs on diff pages with diff percentage point values.


Figure 12.4 KPIs on diff pages in descending sort order.

The Diff Bins By Revisions is also extended from the usual Bins By Revisions chart. All the positive diffs or Improvements, shown in green, are above the horizontal axis and all the negative diffs or Deteriorations in red are shown below the axis. Here, each bar shows the relative portions of items that changed, whether improved or deteriorated, out of all the items in terms of percentage. For example, consider that there are 4 Quality Properties for 2 Artifacts configured in your project. Thus there are total 8 items. If 4 items showed improvements and 2 showed deterioration then the green bar would show 50% and the red bar would show 25% respectively.


Figure 12.5 Quality Diff Bins By Revisions Chart.