Study on decision making of fresh food supplier selection

As the first process of the supply chain, fresh food supplier is the source of food safety, and also the key factor of the whole fresh food supply chain competition. AHP is used to establish the fresh food supplier selection index system. IT is used to calculate the weight of each evaluation index. Through the establishment of a comprehensive evaluation model, decision maker will comprehensively evaluate the strength of fresh food suppliers.


Introduction
At the early of COVID-19, some fresh food surface were detected COVID-19. Therefore, how to ensure the safety of fresh food has become the most concerned topic. In order to ensure the safety of fresh food, fresh food operators should consider suppliers more comprehensively when selecting suppliers. This paper attempts to establish a comprehensive and systematic index system to reflect the supplier selection and evaluation, which can adapt to the current development, and is expected to provide decision-making support and reference for fresh food enterprises.
The analytic hierarchy process (AHP), proposed by the famous American scholar Professor T.L.Saaty in the 1970s, is a method based on multi-criteria decision-making. The method which integrated qualitative analysis and quantitative analysis is applied to determine the weight of each index in the process of decision-making and planning. It has the advantages of practicality, systematicness and simplicity. The main processes are as follows: (1)build the construction of index system; (2)establish the pairwise comparison judgment matrix; (3)conduct single hierarchical arrangement; (4)conduct total taxis of hierarchy.

Establishment of fresh food supplier selection model
This paper selects some indexes to evaluate the strength of fresh suppliers, and uses AHP to transform them into quantitative indexes for calculation. And then, decompose the factors into several hierarchies, conduct pairwise comparison judgment matrix, determine the relatively important factors in the hierarchies. Finally, the importance of each factor is integrated to rank the total service capacity. so as to evaluate the comprehensive strength of fresh suppliers and select the appropriate fresh suppliers.

Chicken product supply chain
The construction of index system is the benchmark of evaluation and calculation.The construction ideas of supplier selection evaluation index system are as follows: first, based on the previous research of supplier selection evaluation system, through the analysis of the connotation of supplier selection evaluation, the basic elements of fresh supplier are determined, and all elements are comprehensively considered.According to the principle of determining the index, the initial index system is designed.Second, adjust the initial index system according to the characteristics of the epidemic period to make it more in line with the actual situation.Finally, a fresh supplier selection index system is formed, which includes four first-class indexes such as product quality, product price, supply capacity and supplier strength, as well as 14 second-class indexes such as freshness quality qualification rate and unit product price, as shown in Table 1.

Construct the judgment matrix and determine the weight and consistency test
In this study, a group of 20 experts, including industry experts and logistics graduate students, were invited to analyze and compare the evaluation indexes of fresh food suppliers formed in the study, and the evaluation indexes were ranked anonymously according to the degree of importance. According to the collected expert consultation data, the geometric mean method is used to collect and calculate, and the comprehensive judgment matrix is obtained. Then, the weight of the matrix is calculated by the sum product method and the consistency is tested. The steps are as follows: 1. The steps of weight calculation by sum product method are as follows: (1) Normalize each column element of judgment matrix (2) The normalized judgment matrix of each column is added by row (3) Pair vector W′ = (W 1 ′ , W 2 ′ … … W n ′ ) t After normalization, the eigenvector W is obtained W=(W 1 , W 2 … … W n ) t (4) Calculating the maximum eigenvalue of judgment matrix 2. Procedure of consistency test Because the evaluation of the judgment matrix is subjective, it is necessary to introduce the correction value RI to check the consistency of the judgment matrix.
Among them, CIis the consistency index, nis the order of judgment matrix,CR is the consistency proportion, and RI is the average random consistency index of the same order . CR = CI RI < 0.1 It means that the judgment matrix is consistent. According to the above steps, table 2-6 is the results of the weight of each judgment matrix and the consistency.

Hierarchical comprehensive sorting
By sorting out the above data, we can get a weight value of B-C evaluation index layer relative to the total goal in Table 7.

Empirical research
Take a fresh food company as an example，there are three alternative suppliers, which are replaced by G1, G2 and G3 respectively. The evaluation team composed of company experts scores the alternative suppliers according to the actual situation, and finally obtains the scores of each evaluation index of the three alternative suppliers. into the established evaluation model to obtain the final score of the supplier, and the score results are summarized in Table 8.