It takes nine days to iron a shirt: the development of cognitive estimation skills in school age children.

Data are presented for 315 elementary school-aged children (K-11) who took the Biber Cognitive Estimation Test, a 20-item test with five estimation questions in each of four domains: quantity, time/duration, weight, and distance/length. Performance showed significant development yearly until around the age of nine years, with much slower development subsequently. No gender effects were found. Age and fund of knowledge correlated with overall test performance. Fund of information accounted for a large proportion of the variance in estimation skills for children 8 years and under, but not for children 9 years and older. Since estimation skills require retrieval and manipulation of relevant knowledge and inhibition of impulsive responding and are necessary in many everyday tasks, it was anticipated that this test may provide a useful measure of judgment and estimations and may correlate with other executive skills in school-aged children.

The Biber Cognitive Estimation Test.

Normative data from 113 participants, and cross-validation data from 49 additional participants, are presented for the Biber Cognitive Estimation Test (BCET), a 20-item test with five estimation questions in each of four categories: time/duration, quantity, weight, and distance. In Study 1, the range of normal answers is provided for each item, and a cut-off for impaired performance is suggested. Although very low IQ or education levels would be expected to invalidate this test as a measure of estimation skills, participants in the current sample made few errors. In Study 2, a cross-validation suggested a slightly more conservative cut-off score for abnormality. Study 3 examined cognitive estimation in demented (dementia of the Alzheimer's type and dementia syndrome of Parkinson's disease) versus intact elderly participants. Results indicated that the BCET was able to distinguish between demented and intact elderly participants.