Validity, reliability and acuity of self-assessment in educational testing

In order to get data about various properties of self-assessment via confidence degrees, a special instrument has been designed, ispired by the Shannon Letter Gessing Game (SLGG) : the Leclercq Letter Guessing game (LLGG). It consists in predicting the next letter of truncated phrases. This cognitive is skill based on the person's knowledge of the statistics of letters sequences in the language used in the text, a skill that cannot be improved or forgotten in a brief delay such as one month. Hundreds of such truncated phrases (from various pages of the same book) have been presented and the respondants had to give a letter and a confidence degree, on various scales (with 4, 10 and 40 degrees on the scale from 0 to 100% of being correct). This game was used to study self assesment : its realism (by calibration), reliability (by repetitivity, test-retest, one month after), acuity or precision or granularity (by the replication curves in the three scales : 4, 10 and 40 degrees). Distributions of values of various indices are provided, constituting a basis for norms. Participants' reactions have been collected. An experience is reported that aimed to study the evolution of the values of various indices under the influence of training.