How are words scored in Dabble?

Dabble rewards quality letters. Words made up of less common letters such as Q and Z are considered more valuable than comparably sized words made of frequent letters such as S and T. This is similar to how letters are valued in Scrabble, but Dabble points are more granular: The value assigned to each alphabet letter is the inverse of the letter’s occurrence ratio (probability) in a reference English vocabulary (i.e., a reference set of unique English words).

The set we are using for point calculation comes from a University of Notre Dame study, which analyzed the main entries of the Concise Oxford Dictionary (9th Edition, 1995). Similar studies of large word sets, including our own, have generated comparable distributions; our conclusion is that for the purpose of point calculation it is more important to adopt a reputable reference vocabulary than to use a custom set with an elusive “perfect” distribution.

Back to scoring: In addition to letter quality, Dabble also rewards the word length; each additional letter after the 4th increases a word’s value by 25%.

To summarize, a word’s value (called merit points in Dabble) is calculated by the following formula,

Merit = Σ_{i = 1…L} (1 / p_i) × 1.25 ^{max(L – 4, 0)}

where L is the word length, p₁ … p_L are the probabilities of each of the word’s letters in the reference vocabulary, and max() is the maximum function.

In addition to the word’s merit points, each submitted word may also collect some bonus points,

• 5+ letter words also remove all immediately surrounding tiles, and each removed surrounding tile earns 3 points.
• Each tile in the submitted word that has a word length requirement above the minimum (3 letters) earns the difference. For example, a tile requiring a minimum word length of 5 earns 5 – 3 = 2 bonus points if it is part of the submitted word.

It is easy to see that a word’s merit points are intrinsic to the word (a function of the word’s letters and length only), while bonus points depend on board variables to add an element of fun unpredictability. Dabble keeps track of your best words based on merit, bonus, and total (merit + bonus) points.