Related Experiment Video
Updated: Jun 26, 2026
A Protocol of Manual Tests to Measure Sensation and Pain in Humans
Published on: December 19, 2016
The impact of test medium on use of visual analogue scales
1Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Canada. cawoods@sciborg.uwaterloo.ca
Objectives:
Visual analog scales are frequently used as a means of allowing participants to rate symptoms during clinical trials. The accuracy and reproducibility of these scales play an important role in determining the experimental value of the data they provide. This study was initiated to compare the data collected using paper- and computer-based (Tablet PC) analog scales to better understand the variability in data provided by a visual analog scale.
Methods:
Thirty participants rated ocular comfort, redness, and clarity of vision (right and left eyes) on a nondemarcated horizontal line on both paper and a Tablet PC. Measurements were taken in the morning between the hours of 8:30 and 10:30 am and again the same day between 2:30 and 4:30 pm.
Results:
The mean difference between the measures recorded in the morning for the 2 media was 2.6 +/- 0.9 (confidence intervals, 2 standard errors of the differences) units on a 100 unit scale, with the Tablet PC having the higher mean measure. The limits of agreement (2 standard deviations of the differences) was 9.4 units. Comparing the difference of the differences (1.0 +/- 1.3) between the 2 methods of measure (morning vs. afternoon) the visual analog scales on the Tablet PC seemed to have good reproducibility of agreement in comparison with the paper version.
Conclusions:
Discrepancy analysis yielded no significant difference and slight bias between paper- and computer-based analog scales. Repeatability of measures using the Tablet PC was also demonstrated. These results suggest that the choice of medium does not significantly influence the outcome for subjective analog scales.
Related Concept Videos
00:54Ratio Level of Measurement
A set of data measured using the ratio scale takes care of the ratio problem and provides complete information. Ratio scale data are like interval scale data, except they have a zero point and ratios can be calculated. For...
01:19Testing a Claim about Standard Deviation
The hypothesis testing for the claim of population standard deviation (or variance) requires the data and samples to be random and unbiased. The population distribution also must be normal. There is no specific requirement on the sample size as the estimation is based on the chi-square distribution.
As a first step, the hypothesis (null and alternative) concerning the claim about...
00:55Interval Level of Measurement
Data measured using the interval scale are similar to ordinal level data because they have a definite arrangement. However, in the interval level of measurement, the differences between data values are meaningful even though the data does not have a starting point.
Temperature is measured using the interval scale. It is measurable data, and the difference between the...
00:55Ordinal Level of Measurement
Data measured using an ordinal scale are similar to nominal scale data, but there is one major difference. The ordinal scale data can be ordered. An example of ordinal scale data is a list of the top five national parks in the...