In a sign that the economy may be picking up, the gross domestic product increased dramatically to an annual rate of 5.7% in the fourth quarter, according to a preliminary estimate released today by the Commerce Department.

That's more than double the 2.2% growth rate during the third quarter.

From October through December, real gross domestic purchases-purchases by Americans of goods and services wherever they were produced-increased 5.1%, compared to 3% in the third quarter.

The department cited a rise in personal, business and government spending and exports as the reasons for the improvement.

Exports increased 18.1%, up from 17.8% in the third quarter.

Imports rose 10.5%, compared to 21.3% in the third quarter.

Consumers paid more for some products. The price index for gross domestic purchases increased 2.1%, compared with 1.3% during the third quarter.

Personal consumption expenditures increased by 2%, compared to the 2.8% rate in the third quarter.

Residential fixed investment, which includes housing, increased 5.7%, compared with an 18.9% increase in the third quarter.