# Facial Soft Tissue Thickness Values for Romanian Adult Population
## 2 Materials and Methods
### Statistical Analysis  
The distribution of facial landmarks and other personal data was examined using Exploratory Data Analysis for the entire dataset, between sexes, and within three weight categories. Correlations among landmarks were computed on the entire dataset and on sexes. Inferential statistics techniques, such as the [PERSON]'s exact test, the Mann-Whitney (Wilcoxon) test, and the Kruskal-Wallis test, helped assess the variability of facial landmarks among categories/groups defined by sex or by weight category. All tests were non-parametric since the distributions of all facial landmarks are not normal, as reported by the Shapiro-Wilk test of normality (see Section 3).  
Data were prepared and analyzed with R programming language [14]. The _tidyverse_ ecosystem of packages (_dplyr_, _tidyr_, _readr_, _string_) [15] was the main tool for data preparation tasks. Exploratory data analysis relied mainly on two packages, _gtsummary_[16] and _ggplot2_[17] (which is part of the tidyverse). Tables 2 and 3 were generated with packages _gtsummary_ and _flextable_[18].  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Variable** & **Statistic** & **Overall, N = 100** & **Female, N = 42** & **Male, N = 58** & _p-Value 1_ \\ \hline
**age\_years** & Median (IQR) & 52 (42, 65) & 54 (38, 67) & 52 (42, 59) & 0.4 \\
**height\_mm** & Median (IQR) & 168 (165, 176) & 165 (160, 167) & 174 (168, 178) & \textless{}0.001 \\
**weight\_category** & & & & 0.4 \\ a.Underweight & n (\%) & 50 (50\%) & 21 (50\%) & 29 (50\%) & \\ b.Normal weight & n (\%) & 42 (42\%) & 16 (38\%) & 26 (45\%) & \\ c.Overweight & n (\%) & 8 (8.0\%) & 5 (12\%) & 3 (5.2\%) & \\
**supraglabella** & Median (IQR) & 2.80 (2.00, 3.00) & 2.80 (2.15, 3.00) & 2.75 (2.00, 3.00) & 0.3 \\
**glabella** & Median (IQR) & 3.10 (2.80, 3.30) & 3.10 (2.73, 3.20) & 3.10 (2.92, 3.30) & 0.7 \\
**nasion** & Median (IQR) & 3.15 (2.77, 3.92) & 3.00 (2.62, 3.50) & 3.40 (2.92, 4.00) & 0.030 \\
**rhinion** & Median (IQR) & 2.00 (1.88, 2.50) & 2.10 (1.83, 2.58) & 2.00 (1.90, 2.50) & 0.5 \\
**mid\_philtrum** & Median (IQR) & 5.00 (4.25, 5.60) & 5.20 (5.00, 5.40) & 4.80 (4.00, 5.60) & 0.11 \\
**supra\_matelae** & Median (IQR) & 5.60 (4.27, 7.00) & 6.00 (4.20, 6.50) & 5.60 (4.53, 7.07) & 0.8 \\
**pogonin** & Median (IQR) & 4.00 (3.10, 5.45) & 4.60 (3.18, 5.60) & 3.50 (3.10, 5.00) & 0.4 \\
**gnathion** & Median (IQR) & 3.40 (2.80, 4.30) & 4.05 (2.85, 4.60) & 3.05 (2.73, 3.90) & 0.11 \\
**l\_mid\_supraorbital** & Median (IQR) & 3.00 (2.80, 3.50) & 3.00 (2.80, 3.98) & 3.00 (2.90, 3.50) & 0.7 \\
**l\_mid\_infraorbital** & Median (IQR) & 2.50 (2.10, 2.90) & 2.40 (2.10, 2.90) & 2.55 (2.30, 3.00) & 0.4 \\
**l\_zygion** & Median (IQR) & 3.10 (3.00, 3.53) & 3.10 (3.00, 4.00) & 3.10 (2.92, 3.50) & 0.3 \\ r\_mid\_supraorbital** & Median (IQR) & 3.00 (2.50, 3.10) & 3.00 (2.50, 3.62) & 2.90 (2.50, 3.10) & 0.5 \\ r\_mid\_infraorbital & Median (IQR) & 2.55 (2.08, 2.80) & 2.50 (2.00, 2.80) & 2.60 (2.10, 2.80) & 0.8 \\ r\_zygion & Median (IQR) & 3.10 (2.90, 3.70) & 3.20 (3.00, 3.60) & 3.00 (2.83, 4.00) & 0.2 \\ l\_mid\_zigomatic & Median (IQR) & 3.10 (2.80, 3.90) & 3.15 (3.00, 4.00) & 3.10 (2.50, 3.60) & 0.057 \\ r\_mid\_zigomatic & Median (IQR) & 3.10 (3.00, 3.60) & 3.10 (2.62, 3.80) & 3.10 (3.00, 3.60) & 0.6 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Descriptive characteristics of parameters studied in relation to sex.  
All statistical tests were performed in base R. The correlation plot was produced with the _corrplot_ package [19]. Statistical test results and charts were obtained using the _ggstatsplot_ package [20] which computes and displays the following parameters for each test: the statistics, the \(p\)-value, the effect size, and the 95% confidence interval of the effect size.