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TESCAN Scoring Terminology

Difficulty Level
The ratio of the number of correct responses to the number of total responses for an item. Values range from zero to one. Difficult items have values close to zero and easy items have values close to one.

Discriminating Power
The ratio of the number of correct responses to an item by the upper 27% of the distribution minus the number of correct responses by the lower 27% of the distribution to one-half of the total number of individuals in the upper 27% and lower 27% of the distribution. You get a positive item discrimination when more students with the highest overall scores answer the item correctly than the students with the lowest overall scores.

Kuder-Richardson Reliability Coefficient
Shows the consistency of measure expected from general administrations of the same test. Values approaching one show increasing reliability. For teacher made tests, values which exceed 0.35 show some level of reliability.

Mean
The arithmetic average.

Median
The score or number which divides the scores into two equal parts.

Mode
The score occurring most frequently.

Range
The point spread between the highest and the lowest score.

Standard Deviation
Shows the extent of heterogeneity of the group tested. The greater the standard deviation, the wider the distribution of scores will be. The standard deviation is the squared distance from each score to the mean.

Standard Error of Measurement
Used in determining the significance between different scores. There is a 2/3 probability that a student's TRUE score is within the obtained score plus or minus the standard error of measurement.

Stanine Score
A normalized score on a nine-point one digit scale in which the successive score values represent intervals of one-half of a standardized deviation with the middle interval set at five, and in which the proportion of examinees at each score is the proportion of the normal curve corresponding to the interval.

Variance
The difference between scores in a distribution.