## 3 Results
### Logistic Regression Analysis on Self-Reported Overall Fatigue and Musculoskeletal Pains
#### 3.4.3 Logistic Regression Analysis on Upper Limb Pain  
The results of logistic regression on upper limb pain are presented in Table 13. 446 subjects were classified into two groups depending on the complaint of upper limb pain. The power of explanation of the model was acceptable (Nagelkerke value = 0.135), and the model seems to fit quite well (\(\chi^{2}\) = 2.551, significance value = 0.863). The overall rate of correct classification (classification accuracy) was estimated as 78.7%.  
Gender (\(p\) = 0.007), work experience (\(p\) = 0.020), and exposure to fumes and dust (\(p\) < 0.001) were the risk factors for upper limb pain. Complaints of upper limb pain among females was 2.342 times more likely than for males. Complaints of upper limb pain among those who have three to four years of work experience was 3.224 times more likely than those who have less than two years of work experience. Complaints of upper limb pain among those who have more than five years of work experience was 2.640 times more likely than those who have less than two years of work experience. Complaints of upper limb pain among those who have more than four ADHE of fumes and dust exposure was 4.033 times more likely than those who have less than two ADHE of fumes and dust exposure.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & \multirow{2}{*}{**N**} & \multirow{2}{*}{**\%**} & \multirow{2}{*}{**B**} & \multirow{2}{*}{**\(p\)-Value**} & \multirow{2}{*}{**Exp(B)**} & \multicolumn{2}{c}{**95\% C.I. for EXP(B)**} \\ \cline{5-8}  & & & & & & **Lower** & **Upper** \\ \hline Gender & & & & & & & \\ Male(ref) & 363 & 81.4\% & & & & & \\ Female & 83 & 18.6\% & 0.776 & 0.007 * & 2.172 & 1.236 & 3.819 \\ Work experience & & & & & 0.020 * & & \\ \(<\)3(ref) & 85 & 19.1\% & & & & & \\
3–5 & 70 & 15.7\% & 1.171 & 0.009 * & 3.224 & 1.344 & 7.736 \\ \(\geq\)5 & 291 & 65.2\% & 0.971 & 0.010 * & 2.640 & 1.256 & 5.550 \\ Fumes and dust & & & & \(<\)0.001 * & & & \\ \(<\)2 (ref) & 273 & 61.2\% & & & & & \\
2–4 & 71 & 15.9\% & 0.438 & 0.200 & 1.549 & 0.793 & 3.027 \\ \(\geq\)4 & 102 & 22.9\% & 1.395 & \(<\)0.001 * & 4.033 & 2.381 & 6.833 \\ constant & & & & \(-\)2.735 & \(<\)0.001 * & 0.065 & & \\ \hline \hline \end{tabular}
* * Significant at 0.05, Note: ref = reference, C.I. = confidence interval.  
\end{table}
Table 13: Results of logistic regression on upper limb pain.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & \multirow{2}{*}{**n**} & \multirow{2}{*}{**\%**} & \multirow{2}{*}{**B**} & \multirow{2}{*}{**\(p\)-Value**} & \multirow{2}{*}{**Exp(B)**} & \multicolumn{2}{c}{**95\% C.I. for EXP(B)**} \\ \cline{5-8}  & & & & & & **Lower** & **Upper** \\ \hline Noise & & & & 0.095 & & & \\ \(<\)2 (ref) & 212 & 47.5\% & & & & & \\
2–4 & 74 & 16.6\% & 0.962 & 0.083 & 2.617 & 0.881 & 7.776 \\ \(\geq\)4 & 160 & 35.9\% & 0.935 & 0.040 * & 2.546 & 1.042 & 6.224 \\ Awkward posture & & & & 0.045 * & & & \\ \(<\)2 (ref) & 167 & 37.4\% & & & & & \\
2–4 & 82 & 18.4\% & \(-\)0.005 & 0.994 & 0.995 & 0.262 & 3.778 \\ \(\geq\)4 & 197 & 44.2\% & 1.011 & 0.03* & 2.749 & 1.050 & 7.199 \\ constant & & & \(-\)3.673 & \(<\)0.001 * & 0.025 & & \\ \hline \hline \end{tabular}
* * Significant at 0.05, Note: ref = reference, C.I. = confidence interval.  
\end{table}
Table 12: Results of logistic regression on backache.