## 3 Results
### Test-Retest Reliability
#### 3.1.2 Test-Retest Differences between Second and Third Test Data Series  
After finding differences between test\({}_{1}\) and test\({}_{2}\) data series in one-fifth of the cases in our sample, we explored whether better or perfect test-retest reliability can be reached by further analyses in these cases. This was motivated partly by the fact that, for the majority of the cases, the test\({}_{1}\) and test\({}_{2}\) datasets were identical. Following the procedure described in the Section 2, we ran another EFE analysis (test\({}_{3}\)) on each of the 12 recordings and conducted test\({}_{2}\)-test\({}_{3}\) comparisons. From the 12 cases, 5 (3 in the ASD, and 2 in the NT group) showed identical test\({}_{2}\) and test\({}_{3}\) datasets--these were \"stabilized\" for test\({}_{3}\). In 7 cases, test\({}_{2}\)-test\({}_{3}\) comparisons still revealed differences. Table 3 summarizes the case flow for repeated AEFEAs.  
Of the 7 individual dataset pairs with remaining differences in test\({}_{2}\)-test\({}_{3}\) comparisons, 6 showed the same ratios of differing data points in test\({}_{2}\)-test\({}_{3}\) as in test\({}_{1}\)-test\({}_{2}\) contrasts. In one case (subject #65; see Appendix A Tables A and A) there were _more_ mismatching data points in the test\({}_{2}\)-test\({}_{3}\) comparison than in the test\({}_{1}\)-test\({}_{2}\) comparison. The absolute values of the test-retest differences between the corresponding data points were again low, in the [\(-\)0.1; 0.1] range. All the 7 (subjects) \(\times\) 8 (emotions) residual difference means remained below 0.001. The final distribution of percentages of differing data points in test\({}_{2}\)-test\({}_{3}\) contrasts is shown in Figure 2 (analogously to the test\({}_{1}\)-test\({}_{2}\) differences previously shown in Figure 1).  
We explored the residual differences for these 7 subjects; see data for individuals in Appendix A Table A. All the remaining differences are small, with the single highest value being 0.069 (subject #94, _Happy_). Although this is close to a 7% difference on a 0-1 scale, this is a single outlier difference value in the total dataset including data points in the order of magnitude of roughly 11.5 million (i.e., 72 contrasts \(\times\) -20,000 intensity data points \(\times\) 8 emotions).  
By observing various characteristics of the 7 cases, we attempted to identify any factor that could potentially underlie the lack of \"stabilization\" (such as group, age, gender, position in the list of data series, video sampling rate, etc.). We failed to identify any such potential factor. In addition, we ran group comparisons along several of these case variables, comparing subject groups corresponding to their stabilized vs. non-stabilized data series. Neither comparing a group of 48 cases to another group of 12 cases (with identical vs. nonidentical data series pairs in test\({}_{1}\)-test\({}_{2}\)), nor comparing a 53-case group  
\begin{table}
\begin{tabular}{c c c c} \hline  & **ASD Group** & **NT Group** & **Total** \\ \hline Number of input cases for test\({}_{1}\) and test\({}_{2}\)/number & 29/23 & 31/25 & 60/48 \\ of identical test\({}_{1}\)–test\({}_{2}\) data series & 6/3 & 6/2 & 12/5 \\ \hline Number of input cases for test\({}_{3}\)/number of & 3 & 4 & 7 \\ \hline Remaining “non-stabilized” data series after test\({}_{3}\) & 3 & 4 & 7 \\ \hline \end{tabular}
\end{table}
Table 3: Case flow for subsequent tests (FR8 analyses) and the number of identical test\({}_{n-1}\)–test\({}_{n}\) data series.  
to a 7-case group (identical vs. nonidentical data series pairs in test\({}_{2}\)-test\({}_{3}\)) revealed any significant cross-group differences. Additionally, as shown in Table 3, the two groups were very balanced in terms of ratios of identical/nonidentical data series pairs.