Ah, the science of crowd estimates. If you’re determining the size of a protest, and you print a number the organizers think is too small, you’ll get angry letters for weeks. Pick too large a number, and those who disagree with the protesters will think the paper is taking sides. Ask the cops? They’re too smart. Many have stopped giving crowd figures, knowing they’ll just get criticized even if the number is exactly right. Dick Rogers, the Chron’s reader representative, is critical of how is own paper came up with a figure of 30,000 for a May 1 immigration rally. He offers suggestions as to how the Chron can do a better job in the future because “there’s one thing you really can count on — this won’t be the last demonstration in San Francisco.”