Why use or not use sidebar inside the content area?

Question

Are there any studies of users response to having a sidebar integrated to the main content area (such as facebook) and sidebar outside the content area (such as Google)?

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The sidebar inside the content area is very common, but there has to be a reason Google is opting for that interface (outside content); I've also seen it in other websites recently.

The cons of inside: it might have problems on small screens, and depending on the content more space is not necessarily better... Could having a larger content area such have its drawback compared with a more focused and smalled area?

Answer 1

INSIDE

• perfect the website layout for a certain width (e.g. 980px, as is recommended for the iPad)
• stronger layout structure (layout is less likely to break)
• newspaper-like columns: it is easier for the eye to read in columns with certain number of words than it is to read text running over the whole screen
• depending on content: typical facebook posts might not fill a bigger page or look strange if you post a few words with an image beside the text, it might look better if the text is spread over two or three lines rather than just one (see facebook's new timeline concept: there are two sides, like to columns now rather than only one for each post)

OUTSIDE

• using the whole screen, meaning not allowing "white spots". One google manager recently showed me a google product page stating "there, can you see that white space? Google does not like white spots on pages, so we're going to fill that soon with this and this".
• giving users something like a "fullscreen" experience
• being able to add additional content (on free sites often filled with ads)

Answer 2

Blocks of text tend to become harder to read the wider the viewport becomes. By capping it (e.g. via max-width) and inserting whitespace on either side, one can maintain presentation while providing some form of responsive layout below the maximum width. You don't want to have a large amount of whitespace between the main content and the sidebar, either, as it becomes less discoverable.