The mood around the US economy continued to be upbeat and a key index of economic indicators rose for the third month in a row, the private Conference Board said Thursday in New York. According to The Conference Board, the index rose 0.4 per cent in December, following a 0.2-per-cent increase in November and a 0.6-per-cent rise in October. However, economists had been expecting a considerably greater improvement in December. "Recent data reflect an economy that ended 2011 on a positive note and the (index) provides some reason for cautious optimism in the first half of 2012," Ken Goldstein, an economist at The Conference Board, said in a statement. "This somewhat positive outlook for a strengthening domestic economy would seem to be at odds with a global economy that is losing some steam. Looking ahead, the big question remains whether cooling conditions elsewhere will limit domestic growth or, conversely, growth in the US will lend some economic support to the rest of the globe. " The index is put together using 10 indicators, including initial claims for unemployment insurance, manufacturers' new orders for various types of goods, consumer confidence and building permits. For the first time since 1996, The Conference Board implemented a comprehensive revision of some components of the index, and the results that were made public Thursday reflected the new rules.