Since the main goal of Round 2 was to determine the degree of consensus among the Delphi panel members, descriptive statistics were used to calculate central tendency and variability: (1) mean (M) as central tendency; and (2) standard deviation (SD) and quartile deviation
(QD) as variability.
The quartile deviation (QD) is a measure of dispersion used only with the median and indicates the dispersion of the data in the middle half of the distribution.
Finally, we compute the quartile deviation and use it with the median.
The quartile deviation is somewhat similar to the range because it includes measurement of the difference between two values, but the values are in the middle half of the distribution.
For the data in exercise 1, calculate the first and third quartiles and the quartile deviation.
"Q" represents the Quartile Deviation (or semi-interquartile range).
We calculated the mathematical medians and quartile deviations for all respondents' ratings on each question item, using the SPSS computer program (SPSS, Inc., 1988).
These quantifiable results can be expressed as percentiles, standard deviations from the mean, quartile deviation
and the per cent of items responded to correctly by the involved learner.
Constructivism stresses evaluating the everyday products and processes of learners in the classroom setting, not a one shot test score such as percentile rank, standard deviation, and/or quartile deviation
from taking a standardized or criterion referenced test.
Generally, the scores are provided in terms of percentiles, although standard deviations, stanines, quartile deviations
, and grade equivalents may also be used to indicate student achievement.