One month, a market report shows 300 homes for sale, and the next month the report shows only 298 homes for sale. Yep, that happens. Real estate data, by its very nature, is always changing. Maybe an agent entered a status change a few days late, or didn't enter a new listing for several days after it was active - any number of things can happen in a given month that impact the data. It doesn't mean the first number reported was wrong, it means that the system received new information that it didn't have before. One of the benefits of an interactive platform like Domus Analytics is that it accounts for all that new data, to always present the true picture of what happened in the market.
Even so, some users would prefer that the data never change. Well, not only is this not really feasible in a real-time database, but it would be wrong. Just because a report didn't display all of the New Listings on a given date, doesn't mean that they didn't exist. Market reports, when they're done right, should accurately reflect the state of the Market, and not be artificially locked in to the state of the data on a given date.