Building a reliable poker database
Before analyzing statistics, it is important to make sure that the database itself is reliable. Incorrect hand histories, missing sessions, duplicated files, or incomplete information can produce misleading conclusions. A serious review should therefore begin with checking the quality and size of the sample.
The larger the sample, the more useful the conclusions usually become. Some statistics can become informative relatively quickly, while others require tens of thousands of hands before clear tendencies appear. For example, a player's overall preflop aggression may stabilize faster than a specific river decision frequency.
The type of game also matters. Cash games, tournaments, heads-up games, short-handed tables, and different poker variants produce different statistical profiles. A statistic that looks unusual in one format may be perfectly reasonable in another.
Players should also separate different limits, sites, formats, and game types whenever possible. Combining very different environments can make the resulting numbers harder to interpret. If a player has hands from several stakes, it can be useful to compare them independently and determine whether the same tendencies appear everywhere.