Back in February, the index -- which tries to measure upbeat or positive economic news -- was 46.5.
In March it slumped to 43.2.
April's count was 46.6. The numbers in March may have reflected bad news related to the tsunami and devastation in Japan.
ESI's numbers are calculated by in-depth "mood" analysis of national news coverage across 15 daily newspapers. It is reported on a scale of 0 to 100; the higher the number, the more positive the publication sentitment, the higher the number.
As stated by a news release from Dow-Jones: "This indicator is calculated through Dow Jones Insight, a media tracking and analysis tool. The technology used for the ESI also powers Dow Jones Lexicon, a proprietary dictionary that allows traders and analysts to determine sentiment, frequency and other relevant complex patterns within news to develop predictive trading strategies."