## 5 Results
### Cluster Analysis
Nonetheless, not all the SLD clusters turned out to be significantly different from TD for all the variables, indicating varying degrees of impairment for the different clusters. Particularly, it could be observed that the SLD clusters were not significantly different from TD for all the variables, indicating that the cluster of TD children was significantly different from TD for all the variables. Figure 5: Mean \(Z\)-scores obtained in the reading (text, word, non-word), writing (word, non-word, sentences), and calculation (number reading, number writing, counting, addition and subtraction, multiplication) tasks in the 4 different clusters. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Cluster** & **1** & **2** & **3** & **4** & & \\ \hline \multirow{2}{*}{**Re\_W\_errors**} & \multirow{2}{*}{0.45} & \(\mathbf{-2.75}\) & \(-0.23\) & \(-0.98\) & \multirow{2}{*}{26.85} & \multirow{2}{*}{\(<\)0.001} & 1 vs. 2, 4 \\  & & & & & & **2 vs. 3, 4** \\  & & & & & & 1 vs. 2, 3, 4 \\  & & \(-0.76\) & \(-0.80\) & \(\mathbf{-2.01}\) & 24.49 &  
that the MD cluster (number 3) was not significantly impaired on MO_AO, while the RD + WD cluster (number 4) was not significantly impaired on either MO_VO or MO_AV. The profiles of the four clusters on the overall STM variables are illustrated in Figure 6. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variable** & **F (3,78)** & \(p\) & **Partial eta2** &
\begin{tabular}{c} **Post hoc** \\ **(Cluster)** \\ \end{tabular} & \(p\) \\ \hline MO\_VV & 6.169 & 0.001 & 0.192 & 1 vs. 3 & 0.014 \\  & & & & 1 vs. 4 & 0.035 \\ MO\_VO & 8.032 & \textless{}0.001 & 0.236 & 1 vs. 2 & \textless{}0.001 \\ MO\_AV & 7.342 & \textless{}0.001 & 0.220 & 1 vs. 3 & 0.032 \\ MO\_AO & 6.217 & 0.001 & 0.193 & 1 vs. 2 & 0.018 \\ MI\_VV & 8.255 & \textless{}0.001 & 0.241 & nn & \\ MI\_VO & 8.249 & \textless{}0.001 & 0.241 & 1 vs. 3 & 0.037 \\  & & & & 1 vs. 4 & 0.005 \\ MI\_AV & 6.359 & 0.001 & 0.197 & 1 vs. 3 & 0.012 \\  & & & & 1 vs. 4 & 0.010 \\ MI\_AO & 9.100 & \textless{}0.001 & 0.259 & 1 vs. 2 & 0.006 \\  & & & & 1 vs. 3 & 0.003 \\  & & & & 1 vs. 4 & 0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Results of the multivariate GLM ANOVA comparing overall STM variables in the 4 clusters. The last two columns refer to differences related to the overall STM variable in the 4 clusters. [PERSON]’s correction was applied to post hoc significance values. Figure 6: Mean scores (Logit-transformed) obtained for the eight overall STM variables in the 4 different clusters. The Logit scale gives a score of \(-3.89\) to the lowest possible performance (raw = 0/25 = 0%), and +3.89 to the highest (raw = 100% = 25/25). Intermediate performances obtain (e.g.) Logit = 0 for raw = 50%, Logit = +1.1 for raw = 75%, Logit = +2.2 for raw = 90%, etc. See Appendix A for details. The next step involved the analysis of the effects related to all factors characterizing each of the overall STM variables. The results indicated that the number of factors ranged between four (for the two VV variables, involving stimulus, presentation, suppression, and distractors) and one (for the two AO variables, involving stimulus only as all other factors were constrained by the nature of the variable, necessarily sequential, allowing for no suppression and no distractors). Table 5 shows the results of the series of repeated-measures ANOVA conducted on each of the overall STM variables. The post hoc analyses refer to differences in clusters for the overall variables. Significant interactions with cluster mainly concern stimulus (differences between colours and letters emerging for MO_VV, MO_VO, MO_AV, MI_VV, and MI_VO), but also presentation (sequential versus simultaneous) turned out to interact with cluster for MO_VO and for MI_VO, while the presence of distractors significantly impacted cluster-related differences in MI-VV. A triple interaction stimulus by articulatory suppression by cluster emerged for MO_AV.