But in a recent study they declared that forty percent of the tweets captured over a two-week period were "pointless babble."

VOA: special.2009.09.14

The study involved forty-four traders and their profits and losses over a twenty-month period ending in two thousand seven.

VOA: special.2009.02.25

The study examined employment records for eight cities in Minnesota for a three-year period through two thousand six.

VOA: special.2009.05.27

They used information gathered over a period of 20 years, until 2003, in the Framingham Heart Study.

VOA: special.2009.01.21

The only difference is they have one period a day where they study Islam."

VOA: standard.2010.07.12