Custom Reports calculation bug when Action Dimension and Goals used

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1

Using Matomo 3.13.0 and Custom Reports 3.1.23 (this also happened with previous Matomo / Custom report versions) we see a calculation bug when An Action Dimension is used in conjunction with a GoalID metric.

As a basic example if we had the following:
Action Dimension name “Color” with red, blue, green as values that get set on Page 1 and a goal, “Goal 1” also being set on page 1 unrelated to the color value and being set just by accessing the page (which can be set multiple times per visit), the goal count is incorrect in a Custom report where the Action dimension “color” is used as a Report dimension and “Goal 1 Conversion Count” is used as a metric.

Basically what we see is that the goal count metric isn’t constrained by each Action dimension value row. An example with the following sample traffic:

Visitor 1
Visit 1: Page 1, color red, goal fired
Visit 2: Page 1, color blue, goal fired
Visit 3: Page 1, color green, goal fired

Visitor 2
Visit 1: Page 1, color red, goal fired
Visit 2: Page 1, color green, goal fired

In a custom report defined as above we should see:

Color, GoalID Conversion
red,2
blue,1
green,2

What we actually see is:

Color, GoalID Conversion
red,5
blue,1
green,5

Glancing through the code it seems to be an issue in the Querybuilder.php file. Happy to share real data/repro cases as needed to help diagnose and resolve. Thanks.

2

Hi,

I have tried to recreate this exact scenario:

I have an action dimension that grabs the colour from the URL, and goal that is converted when the URL contains colour. Here are the visits:

image
image731×732 25.1 KB

Here is the report:

image
image1212×408 8.01 KB

This seems to be in order?

3

The bug occurs when you have multiple goal conversions with different action dimension values in the same visit. If in one of those visits you have an action with color =red and another action with color = blue, each converting the goal, you’d have an overcount where red would show 3 (because it would also count the blue goal conversion in the same visit) and blue would also show 3 because of the same issue.