4. Market investigation and research on the influencing factors of consumers' choice of New
4.7. Pre-survey
For the scale part of the questionnaire (the fourth part), firstly we completed the preliminary survey before the formal survey to ensure that the questionnaire used in the formal survey is scientific and effective. If there is any problem, the questionnaire can be modified in time. The preliminary survey was distributed randomly on the internet, with a total of 50 questionnaires. After collecting data, the reliability and validity of the questionnaire were analyzed, and the final version of the questionnaire was determined. Then the questionnaire was conducted and the questionnaire was officially started.
4.7.1. Reliability test of questionnaire
Reliability test: It refers to the reliability of the measured results of the scale prepared.
The higher the reliability of scale, with the less affected by environmental factors such as time, place. The results tested by this scale are more stable. In this paper, the most commonly used reliability test methods are adopted - Cronbach's ɑ reliability coefficient method.
The formula is:
) 1
1( 2x
2
S S
ik
k
The k is the total number of items in the scale,
S
i2represents the variance of the score for item i,S
2x represents the variance of the total score for all items.The coefficient α is between 0 and 1. The higher the α coefficient is, the higher the reliability of the scale is and the better the internal consistency is. It is generally believed that if the overall reliability coefficient α is between 0 and 0.6, it indicates that the item design quality of the questionnaire scale is poor and some items need to be deleted. If the overall reliability coefficient α is between 0.6 and 0.7, it indicates that some items in the questionnaire scale need to be modified. If the overall reliability coefficient α is between 0.7 and 0.8, it indicates that the reliability of the questionnaire scale is within the acceptable range. If α coefficient >0.85, it indicates that the scale of questionnaire is of use value.
In this research, Cronbach's ɑ reliability coefficient method is used to test the internal consistency of the questionnaire. The results are shown in Table 13. Cronbach's α coefficient is greater than 0.9, indicating that the questionnaire has high reliability and good internal consistency. So the questionnaire has certain use value.
Table 13. Reliability test results
Cronbach's α coefficient The number of items
0.991 18
4.7.2. Validity test of questionnaire
Validity refers to the validity of the scale, which refers to the degree to which the measuring tool or means can accurately measure the things to be measured. The validity test is to check the validity of the scale in the questionnaire. Generally speaking, it indicate that the measurement results are more consistent with the content to be investigated, and the more effective the questionnaire is. Validity test generally includes content validity test and construct validity test.
4.7.2.1. Content validity test
Content validity also known as face validity or logical validity. It refers to whether the items set in the questionnaire scale are reasonable, whether these items can represent the content or topic to be measured, and whether there is a logical relationship between these items and the variable factors to be measured.
The design of the questionnaire in this paper is based on previous theoretical research, and refers to a large number of literature and scales. During the design of the questionnaire, experts' opinions were adopted and a lot of modifications were made. It can be seen that this questionnaire has good content validity.
4.7.2.2. Structural validity test
Structural validity test refers to the correlation between scale items and measurement results in the questionnaire. This chapter uses principal component analysis and Exploratory Factor Analysis (EFA), the common factor is extracted with the characteristic root value >1.0 as the standard.
After item selection and factor analysis, all the original 18 items are retained in the scale part of the questionnaire on influencing factors of consumer behavior of New Energy Vehicles (NEV). The KMO value is 0.980, higher than 0.9, and the Bartlett's spherical test χ2 value is 15081.417 (P<0.001), the P is smaller than 0.05. In conclusion, the results show that the questionnaire is suitable for factor analysis. One common factor is extracted in this research, the loading value (loading value indicates the integrating degree of the items in the common factor) is above 0.9, higher than 0.6, and the cumulative percentage (cumulative percentage indicates the total explanation of the questionnaire) of explained variance is 88.160%, higher than 60%, these show the questionnaire has a good structure validity. The result is shown in the Table 14 and Table 15.
Table 14. KMO test and Bartlett’s spherical test
KMO test 0.980
Bartlett’s spherical test
χ2 15081.417
df 153
P <0.001
Table 15. Component matrix factor analysis
Item Loading value
10.1 The public infrastructure of the NEV (fraction of coverage and
quantity of the charging station) 0.910
10.2 The selling price of the NEV 0.915
10.3 The daily cost of the NEV (daily charging cost) 0.906
10.4 The NEDC of NEV 0.928
10.5 The charging time of the NEV 0.930
10.6 The maintenance and after-sales costs of the NEV 0.931
10.7 The battery life span of the NEV 0.936
10.8 The battery safety of the NEV 0.934
10.9 The driving feeling of the NEV (strong acceleration, low noise) 0.960 10.10 The exterior and interior design of the NEV 0.952 10.11 The functions and configurations of the NEV 0.958
10.12 The government subsidies of the NEV 0.946
10.13 The government subsidies of the NEV 0.956
10.14 Green Concept：The NEV are conducive to energy saving and emission reduction, meet the needs of sustainable
development, and belong to the green travel.
0.959
10.15 The social development trend 0.951
10.16 The brands of the NEV 0.957
10.17 The influence of family, friends, colleagues, etc. 0.947 10.18 The influence of advertising, media, celebrity idols, etc. 0.924
* It only extracts a common factor and cannot rotate
* The order of this table is based on the order of the questionnaire questions, which are randomly generated to ensure the validity of the survey.