Such variations were very common up until the 1940s and still occur, though not as often.

These variations usually occur in seconds to minutes or hours.

They suggest that such variation can occur at four levels.

Because the dance is led and followed at the level of individual steps, these variations can occur from one step to the next.

Sharp variations in a time series can occur for many reasons.

These variations occur on many different time scales (and are still a subject of research).

Until then, patients must rely on limited information, and wide variations in practice will occur.

Some variations can also occur according to the individuals or to their stage of maturity.

The first variation on the theme occurs at measures 19-34.

Variation occurs between speakers, and even within the speech of a single person.