Significant
Difference Thresholds for Each Test Type Threshold Frequency Threshold Frequency Expressed as a Percentage Glucose (a) 3 2 4 1 4 2 5 3 6 8 5.6 1 12 1 10 19 50 1 Potassium (b) 0 1 4 1 0.1 1 5 2 0.2 4 6.2 1 0.4 1 7 1 0.5 11 10 5 0.8 1 12.3 1 1.0 1 25 1 WBC count (c) 0 1 1.4 1 0.1 1 5 2 0.3 1 9 1 0.4 2 10 7 1 1 15 2 3 1 20 2 25 1 30 1 Platelet count (c) 1 1 0 1 3 1 7 1 5 1 10 5 6 1 15 2 9 1 20 3 15 1 25 2 20 2 50 1 Abbreviation: WBC, white blood cell.
border irregularity) on absolute detection threshold, although this effect approached significance (speaking descriptively, participants tended to report slightly higher
difference thresholds for lesions demonstrating border irregularity than for lesions demonstrating asymmetry).
For each subject, the mean lower threshold value was subtracted from the mean upper threshold value to obtain the
difference threshold, which is the largest line-length difference that subjects did not discriminate.
Each technique allows for the calculation of a threshold value and a measure of variability about that threshold, typically called the
difference threshold or just noticeable difference (JND).