true count

[edc]

Many black jack books say to convert the running count to true count divide by the remaining decks. This appears to be averaging the high cards(or low) over the remaining decks. In a 6 deck shoe a count of plus five in the first deck would convert to a plus one. However; the five high cards may be in the first deck or second, etc. Have there been any studies showing that the true count computed as an average is the best method or have other ways been tried?