## 3 Materials and Methods
### Data Collection  
A questionnaire was designed with a web tool for data collection. The questionnaire was composed of three parts. The first part describes an overview of the survey. The second part is intended to collect demographic data concerning the respondents' position, professional background, years of work, and their firm's professional category. In the third part, the respondents are invited to mark the importance level of the 33 factors. A 1 to 7 Likert scale is used for this measurement, where one represents exceptionally unimportant, four represents neutral, and seven represents extremely important. This survey was designed so that respondents would not be able to successfully submit their answers if any item in the questionnaire was not answered, as a warning message would be generated.  
The following formula was adopted to determine the sample size [7]:  
\[\text{n}=\text{n1}/(1+\text{n1}/\text{N}) \tag{1}\]  
where n = the sample size; n1 = S2/V2; N = the total population (the number of construction firms = 95,400 [20]); V = the standard error of the sampling distribution = 0.05; S2 = P (1 - P) = 0.5 \(\times\) (1 - 0.5) = 0.25 (S = the maximum standard deviation in the population elements, the total error = 0.1, the confidence level is 95%, and P = the proportion of population elements that belong to the defined class).  
The value of the predefined variables was substituted into the formula mentioned above, and then the sample size n = 100 was derived.  
The online questionnaire was distributed electronically to practitioners working for general contractors across China in October 2018. The total number of invited respondents was 500, from which 112 returned responses (a 22.4% response rate). Among all the returned questionnaires, 109 were found to be valid, and the others were not taken seriously (such as those with the same rating for all items). The valid respondents included 18 top executives, 32 project managers, and 59 department managers. Moreover, all respondents had more than five years of work experience, and over 65.75% of  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Data Collection Year** & **Country/Region** & **GDP Growth Rate** & **Reference** \\ \hline
1988 & United States & Fell from 7.26\% in 1984 to \(-\)0.07\% in 1991 & [7] \\
1990 & UK & Fell from 5.75\% in 1988 to \(-\)10.98\% in 1991 & [4] \\
1999 & Syria & Fell from 134.7\% in 1992 to \(-\)3.55\% in 1999 & [1] \\
2009 & Saudi Arabian & Fell from 11.24\% in 2003 to \(-\)2.06\% in 2009 & [8] \\
2009 & Vietnam & Fell from 7.55\% in 2005 to 5.40\% in 2009 & [23] \\
2013 & Jordan & Fell from 8.57\% in 2004 to 2.0\% in 2016 & [3] \\
2014 & Qatar & Fell from 19.95\% in 2010 to 2.22\% in 2016 & [11] \\ \hline \end{tabular} Note: GDP data from the World Bank website.  
\end{table}
Table 2: The economic downturn extent in previous studies on contractors’ bid/no-bid decision factors.  
them had over 10 years of experience. The position and years of work experience were used to judge the validity of the samples. It is essential to ensure that the participants have sufficient knowledge of BNB decisions and are involved in the decision-making process. For each type of construction, 72.60% of the respondents were from commercial building construction, 12.33% from heavy construction, 10.96% from local public construction, 2.74% from industrial construction contractors, and 1.37% were utility contractors. In terms of the distribution of the respondents' geographical locations, the respondents were distributed over 20 provinces and cities, including Beijing (6), Fujian (7), Guangdong (8), Jiangsu (12), Shandong (8), Shanghai (6), Zhejiang (9), Anhui (4), Guangxi (2), Guizhou (4), Henan (5), Hunan (4), Liaoning (2), Neimenggu (2), Gansu (2), Shaanxi (4), Shanxi (3), Sichuan (5), Yunnan (3), and Chongqing (13). It is difficult to assess the extent to which the samples represent the entire Chinese construction industry. However, the composition of the respondents, to some extent, helps avoid biases.