Table 3.

Potential mediation of the association between near park area and current depression by time spent walking/week (IPAQ questionnaire), perceived stress score (Cohen’s Perceived Stress Scale) and neighborhood satisfaction score (Domain 4 of the WHO-QoL-BREF scale).

Hypothesized mediators	Coefficients#	Estimate	Standard Error
Time spent walking per week	a	-4.84E-05	6.27E-04
	b	-1.28E-03	6.59E-04
	ab (mediated effect)	6.18E-08
	95% CI	(-1.51E-06 - 1.63E-06)
	Significance	Not significant
Perceived stress score	a	-2.05E-06	4.84E-06
	b	1.56E-01	6.24E-02
	ab (mediated effect)	-3.21E-07
	95% CI	(-1.8E-06 - 1.81E-06)
	Significance	Not significant
Neighbourhood satisfaction score	a	-2.83E-06	1.15E-05
	b	-2.15E-01	3.56E-02
	ab (mediated effect)	6.08E-07
	95% CI	(-4.25E-06 - 5.47E-06)
	Significance	Not significant

Notes: Mediation analysis was performed using the ‘product of coefficients approach’ (MacKinnon, 2008; MacKinnon, Lockwood, Brown, Wang, & Hoffman, 2007a).

^#‘a’ and ‘b’ refer to the estimated regression coefficients in the following two equations - M = i₁ + a X+ d Z + e ₁ ; Y = i ₂ + c’ X+ b M + d’ Z+ e₂ (MacKinnon, 2008). M refers to the hypothesized mediator, X is the independent variable (near park area), Y is the dependent variable (current major depression) and Z refers to all confounding variables combined. Standard error of the product of coefficients (ab) was calculated using the following equation – ${\sigma }_{ab}=\sqrt{{\sigma }_a^2{b}^2+{\sigma }_b^2{a}^2}$ and 95% confidence interval (CI) calculated using equation – ab ± 1.96*(σ_ab) Since all the estimated confidence intervals contained 0, we concluded that none of the hypothesized mediating variables had significant mediating effects.