# Developing Productivity-Safety Effectiveness Index Using Data Envelopment Analysis (DEA)
## 5 Discussion
### Limitations  
The study has limitations for data availability and the analysis level, although the integrated measure for evaluating the efficiency of productivity and safety activities is developed and effective methods are applied.  
First, due to the difficulty in collecting data at the industry level, this study only uses public data of productivity and safety performance indexes. However, by collecting more information, we can suggest more useful implications for benchmarking and improving industries' PSEI. Thus, we should consider more input and output variables, such as the amount of safety investment and the production of industries. Other economic indicators related to firm activities, such as technology investment and labor costs, can also be included. A long-term study monitoring the relationship between productivity and safety is effective in understanding the delayed impact of safety investments.  
Second, from a microeconomic perspective, we consider how to internalize safety investments. Safety investments are difficult to prove their effect on firm performance in the short term. Additionally, since safety investments vary across companies in terms of technological, facility, and human aspects, it is also challenging to analyze them on a  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Industry** & **Trend** & **IR** & **FR** & **SR** & **LP** & **PC** & **OR** \\ \hline
2. Textile(except apparel) & Decrease & 3.60 & 1.62 & 0.83 & 98.25 & 99.70 & 95.95 \\
5. Coal and petroleum products & Decrease & 4.49 & 1.97 & 3.72 & 105.05 & 103.70 & 105.13 \\
11. General machinery and equipment & Decrease & 7.39 & 3.33 & 1.77 & 105.50 & 100.30 & 99.63 \\
14. Automobile & Decrease & 6.00 & 2.70 & 1.16 & 98.49 & 100.15 & 90.98 \\ \hline \hline \end{tabular}
\end{table}
Table 10: Decrease trend and statistics of industries.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Type** & **Example of** **Industry** & **Year** & **Score** & \multicolumn{3}{c}{**Input**} & \multicolumn{3}{c}{**Output**} \\  & & & **IR** & **FR** & **SR** & **LP** & **PC** & **OR** \\ \hline  & Precision & 2015 & 94.87 & \(-\)0.16 & \(-\)0.06 & \(-\)0.03 & 0.35 & 3.39 & 0 \\  & instrumental & 2016 & 92.63 & \(-\)0.26 & \(-\)0.1 & \(-\)0.05 & 1.71 & 2.31 & 0 \\  & Electrical & 2015 & 80.80 & \(-\)0.67 & \(-\)0.27 & \(-\)0.12 & 0.05 & 4.08 & 0 \\ input and output &
\begin{tabular}{c} Textile \\ Coal and \\ petroleum products \\ \end{tabular} & 2015 & 74.65 & \(-\)0.91 & \(-\)0.39 & \(-\)0.17 & 0.01 & 4.17 & 0 \\  & 2016 & 62.83 & \(-\)1.92 & \(-\)0.72 & \(-\)1.34 & 3.09 & 0.25 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 9: _Cont._company-by-company basis. However, if data on a company's safety investment performance are available, research could be conducted to assess the effects of reduced accident rates and increased productivity resulting from specific safety investment categories. This could serve as a basis for internalizing efficient safety investments.  
Third, the PSEI can also be analyzed at different levels, such as the national level or the firm level. Although industry-level analysis provides relevant information for policymakers, a national comparison can be effective for strategy formulation of benchmarking developed countries. However, national economic indices differ in terms of definition criteria and data collection methods. To address this issue, we can use International Labour Organization (ILO) or Organisation for Economic Co-operation and Development (OECD) data to ensure consistency at the national level.