Risk Influencing Factor Analysis of Urban Express Logistics for Public Safety: A Chinese Perspective

Table 4

Structural self-interaction matrix (SSIM).

		○	⟶	⟶	⟶	⟶	⟶	⟶	⟶	⟶	⟶
			⟶	○	○	○	○	○	○	○	⟶
				○	○	○	⟶	○	○	⟶	⟶
					⟶	○	⟶	○	○	○	○
						⟵	⟶	⟶	○	⟶	⟶
							○	○	○	⟶	○
								↑	↑	○	○
									⟶	○	⟶
										○	⟶
											↑

⟶: row has an effect on the column; ⟵: column has an effect on the row; ↑: row and column interact; ○: the two factors are irrelevant.