Final results overall
- Central tendency of net scores: mean = 1.5, median = 3
- Distribution: SD = 4.7, skewness = -.4, kurtosis = 2.1, Shapiro-Wilk W = .93, p = .43
- Frequencies:
excellent
= 35, satisfactory
= 32, needs improvement
= 20
- Most consensus:
Are there any proven ways to increase concentration and focus? = needs improvement
×6 + 1E
- Least consensus:
Is learning and memory formation mostly comprised of new synapses forming, or already-existent synapses strengthening? = 2×E
, 3×S
, 4×NI
Comparison to five previous site self-evaluations:
Net score data
_______________Month_/_Year________________
Question_#__|__8/14_____2/14_____11/13_____8/13_____5/13_____5/12
1 | 7 5 3 7 6 7
2 | 7 3 3 6 4 7
3 | 4 1 2 6 4 7
4 | 4 1 2 6 3 7
5 | 4 0 0 6 3 6
6 | 2 0 0 5 3 5
7 | 0 0 -1 3 2 4
8 | -2 -4 -1 2 2 -2
9 | -4 -4 -1 1 1 -3
10 | -7 -5 -4 -2 1 -3

Descriptive statistics
Month/Year: 8/14 2/14 11/13 8/13 5/13 5/12
Medians: 3 0 0 5.5 3 5.5
Means: 1.5 -.3 .3 4 2.9 3.5
SD: 4.7 3.2 2.2 2.9 1.5 4.4
Inferential statistics
Kruskal–Wallis χ² = 13.6, df = 5, p = .02; self-evaluations' net scores are distributed differently. However, no post-hoc comparisons (Dwass–Steel–Chritchlow–Fligner test – Steel.Dwass()
in RcmdrPlugin.EZR
package; see also this reference) achieve p < .05; only the difference between 2/14 and 8/13 came close (t = 2.74, p = .067). These net scores still correlate negatively with order of site evaluation (Kendall's τ = -.25, which converts to r = -.39 using this method; zτ = 2.6, p = .01), indicating a downward trend. The linear model plotted above using the Theil–Sen single median estimator (in the mblm
package) is scorei = .75×timei - .5 + εi; its standardized βtime = .36, not .39.
This month's set has the greatest variance so far, which suggests ratings may be heteroskedastic across time. However, a Brown–Forsythe test (levene.test()
in the lawstat
package) can't reject the null of homogeneous absolute deviations from the median (statistic = 1.7, p = .15).
Discussion
Despite the overall trend since the first evaluation, scores are up since our last evaluation. All pairwise differences are insignificant when comparing ratings aggregated to the question level, but the omnibus test is still picking up overall differences in ranks of scores across evaluations.
I'm still ignoring dependencies across time (e.g., I participated in the last evaluation too) and the hierarchical structure of individual ratings nested within questions, which I'm comparing across evaluation periods. Again, the May '12 scores may not be comparable due to method variance.