Forty percent of the messages on Twitter are "pointless babble" along the lines of "I am eating a sandwich now," according to a study conducted by a US market research firm.

Pear Analytics, based in San Antonio, Texas, said that it randomly sampled 2,000 messages from the public stream of Twitter and separated them into six categories.

The categories were: news, spam, self-promotion, pointless babble, conversational and pass-along value.

Pear said "pointless babble" accounted for 811 "tweets" or 40.55 percent of the total number of messages sampled.

Conversational messages -- defined by Pear as tweets that go back and forth between users or try to engage followers in conversation -- accounted for 751 messages or 37.55 percent.

Pear said tweets with "pass-along value" -- messages that are being "re-tweeted" or passed on by users to their followers -- accounted for 174 messages or 8.70 percent.

Self-promotion by companies was next with 117 tweets or 5.85 percent, followed by spam with 75 tweets or 3.75 percent.

It said tweets with news from mainstream media publications accounted for 72 tweets or 3.60 percent.

Pear said it planned to conduct the study every quarter to identify trends on Twitter, which allows its users to send messages of 140 characters or less to a network of "followers."