The Linear Correlation Coefficient

The linear correlation coefficient measures the strength and direction of the linear relationship between two variables $x$ and $y$ .
The sign of the linear correlation coefficient indicates the direction of the linear relationship between $x$ and $y$ .
When $r$ is near 1 or −1 the linear relationship is strong; when it is near 0 the linear relationship is weak.

Callback before_footer in local_aigrade component should be migrated to new hook callback for core\hook\output\before_footer_html_generation

line 7225 of /lib/moodlelib.php: call to debugging()
line 7292 of /lib/moodlelib.php: call to {closure}()
line 71 of /lib/classes/hook/output/before_footer_html_generation.php: call to get_plugins_with_function()
line 987 of /lib/classes/output/core_renderer.php: call to core\hook\output\before_footer_html_generation->process_legacy_callbacks()
line 97 of /mod/book/tool/print/index.php: call to core\output\core_renderer->footer()