Prediction is a rate enhancement strategy in which the SGD attempts to reduce the number of keystrokes used by predicting the word or phrase being written by the user. The user can then select the correct prediction without needing to write the entire word. Word prediction software may determine the choices to be offered based on their frequency in language, association with other words, past choices of the user, or grammatical suitability. However, users have been shown to produce more words per minute (using a scanning interface) with a static keyboard layout than with a predictive grid layout, suggesting that the cognitive overhead of reviewing a new arrangement cancels out the benefits of the predictive layout when using a scanning interface.