Looker Studio essentials

Setup panel versus Style panel?

Setup controls what the chart shows — source, dimensions, metrics, filters. Style controls how it looks.

Your Sheet gives columns named "Column 1". Why?

Title or blank rows sit above the header row. Use a named range or clean the sheet.

Why does an order ID get summed?

It is numeric, so Looker Studio treats it as a metric. Change its type to text and role to dimension in the data source.

Where should reusable calculated fields be created?

At the data source level, so every report using that source gets them.

Why is SUM(a)/SUM(b) preferred over SUM(a/b) for a rate?

Dividing the totals is correct; averaging per-row ratios weights small rows equally with large ones.

Every metric in a blend is null. Cause?

The join keys do not match in format. Normalise with a calculated field first.

What must a blend join on?

Dimensions shared by the sources, up to five sources total.

One chart ignores the page date control. Why?

It has its own date range set in Setup, which takes precedence.

A filter control affects only some charts. Why?

It only affects charts whose data source contains that field.

What does cross-filtering do?

Clicking an element in one chart filters the other charts on the page.

What is the risk of owner's credentials?

Everyone who opens the report sees data through your access, regardless of their own permissions.

What filter state does a scheduled email PDF use?

The report default, not whatever anyone last selected.

Biggest lever on a slow report?

Extract data, or aggregate upstream — every component runs its own query.

Why set canvas size before building?

Changing it later reflows every component and you reposition by hand.

How do reports behave on mobile?

The canvas scales but components do not reflow. Build a separate single-column page.