## 3 Results  
Length data pointed out statistically significant differences among groups (\(p\) < 0.01); the Medieval population usually showed higher mean values in comparison to other groups. Data referring to heights revealed statistical significance for the nasion-prosthion height (NPH) and nasal height (NLH) variables, with lower mean values being observed in the Domus population. As regards the breadth measurements, statistically significant differences were observed for the variables minimum cranial breadth (WCB), biorbital \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Measurement**} & **Howell’s** & **1 st** & **2 nd** & \multirow{2}{*}{**Agreement (\%)**} \\  & **Code** & **Measurement** & **Measurement** & \\ \hline \hline \begin{tabular}{c} Basin–nasion length \\ \end{tabular} & BNL & 109.2 & 109.8 & 99.5 \\ \begin{tabular}{c} Basin–prosthion length \\ \end{tabular} & BPL & 111.2 & 110.9 & 99.7 \\ \begin{tabular}{c} Maxillary–alveolar length \\ \end{tabular} & MAL & 52.7 & 53.6 & 98.3 \\ \begin{tabular}{c} Nasion–prosthion height \\ \end{tabular} & NPH & 68.6 & 68.7 & 99.9 \\ \begin{tabular}{c} Nasal height \\ \end{tabular} & NLH & 31.0 & 29.7 & 95.8 \\ \begin{tabular}{c} Minimum alveolar height \\ \end{tabular} & 44.4 & 43.7 & 98.4 \\ \
\begin{tabular}{c} Orbital height \\ \end{tabular} & OBH & 31.0 & 29.6 & 95.5 \\
\begin{tabular}{c} Nasal breadth \\ \end{tabular} & NLB & 19.3 & 19.1 & 99.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Percent agreement of the measurement. breadth (EKB), orbital breadth (OBB), and nasal breadth (NLB). A progressive increment in WCB was detected through chronological ages. The NLB showed an unusual result: the Nuragici, Medieval, and Modern groups showed similar values, and only Domus significantly differed from the others (\(p<0.01\)), showing the lowest values (Table 2). The Domus sample showed high values of distance to the Medieval population (544.7) and to the Modern one (330.6). The Modern population showed no similarity to prehistoric populations nor to [PERSON]'s standard. Similar results were obtained using the bootstrap technique on the original data set, without [PERSON]'s standard, allowing us to build up the means and standard errors after 500 iterations for each variable (Table 3). Similar results of UPGMA were obtained using the bootstrap technique on the original data set, without [PERSON]'s standard, allowing us to build up the means and standard errors after 500 iterations for each variable (Tables 3 and 4). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & Medieval & Modern & Nuragici & Domus \\ Medieval & - & 0.0003 & 0.0011 & 0.0005 \\ Modern & \(115.9\) & - & 0.0009 & 0.0004 \\ Nuragici & 544.9 & 379.9 & - & 0.0005 \\ Domus & 544.7 & 330.6 & 87.3 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Squared Euclidean dissimilarity coefficient matrix after 500 bootstrapped iterations: below the diagonal are the relative standard errors, and above the diagonal are the populations’ results. \begin{table}
\begin{tabular}{l c c c c} \hline \hline  & Medieval & Bolton \({}^{1}\) & Modern & Nuragici \\ \multicolumn{1}{c}{Bolton \({}^{1}\)} & 603.8 & & \\ Modern & 117.2 & 293.4 & & \\ Nuragici & 545.0 & 253.8 & 379.9 & & \\ Domus & 544.7 & 279.8 & 330.6 & 87.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Squared Euclidean dissimilarity coefficient matrix obtained for the populations. The similarity among populations is immediately appreciable from the dendrogram (Figure 2). A head emerging from the view tree is the clear differentiation in two clusters separated by Bolton's standard; Nuragici and Domus at the top, and Medieval and Modern at the bottom. Figure 3 displays the D-plot of the first two principal coordinates derived from the principal component analysis (PCA). The first two eigenvalues collectively account for 80.9% of the total variance (59.1% and 21.8%, respectively). Clearly, Domus and Nuragici populations tend to form separate clusters.