*2.3. Theoretical Fundamentals*

## 2.3.1. Research Development

The authors found that the COVID-19 pandemic negatively impacted most businesses, sectors, and industries in Vietnam's economy [1]. In particular, the logistics industry was most affected because localities and countries implemented social distancing orders to limit the movement of people and goods. Therefore, the author realizes that it is necessary to assess the impacts of the epidemic on logistics enterprises and propose solutions to help businesses recover and develop. The research process is carried out by the authors according to the steps shown in Figure 8 below:

After determining the research objectives, the authors selected enterprises to conduct the research. These enterprises must use the same operations in the logistics industry, have similarity of scale, and have appropriate geographical locations to ensure feasible transportation.

After selecting businesses that fulfill the conditions to carry out the research objectives, the authors selected factors to analyze the business situations of logistics enterprises before

and during the pandemic. Then, the authors checked the correlation of these factors to ensure the appropriateness of the data included in analysis and processing.

**Figure 8.** Research process (Source: Researcher).

After examining the correlation between the factors used in the study, the authors used the Malmquist productivity index to assess the impact of the pandemic on the business situation of Vietnamese logistics enterprises for the period 2017–2020. Then, the authors used a super-slack-based model to rank these enterprises, as a basis for choosing the optimal alliance partner to improve business efficiency for logistics enterprises in the future.

After evaluating and ranking the logistics enterprises, the authors used the rankings to make alliances for enterprises. Then, the authors used the Grey forecasting model (GFM) to forecast the business situation of enterprises in the alliance. This forecast aims to provide managers with a complete picture of their alliances as a solid basis for decision making to enable sustainable development.
