. 2019 May 29;14(5):e0215847. doi: 10.1371/journal.pone.0215847

Table 4. Meta regression results (using WTP in $/lb).

	WLS with robust SEs				WLS with cluster robust SEs				Wild bootstrap cluster robust SEs
	(1)		(2)		(3)		(4)		(5)		(6)
	Coeff.	CI	Coeff.	CI	Coeff.	CI	Coeff.	CI	Coeff.	CI	Coeff.	CI
Constant	6.179^*** (2.303)	1.563; 10.796	5.173^** (2.203)	0.757; 9.590	6.179^*** (2.220)	1.616; 10.743	5.173^** (2.025)	1.012; 9.335	6.179^* [0.056]	2.661; 9.894	5.173^* [0.074]	1.903; 8.350
sqrt(n)	-0.065^** (0.027)	-0.119; -0.011			-0.065^** (0.031)	-0.130; -0.000			-0.065^* (0.080)	-0.120; -0.011
n			-0.002^*** (0.000)	-0.003; -0.001			-0.002^*** (0.001)	-0.003; -0.000			-0.002^*** [0.002]	-0.003; -0.001
Year of study	-0.633^* (0.330)	-1.294; 0.028	-0.814^** (0.330)	-1.476; -0.152	-0.633^* (0.359)	-1.371; 0.106	-0.814^** (0.345)	-1.524; -0.104	-0.633^* [0.084]	-1.213; -0.025	-0.814^** [0.030]	-1.371; -0.243
Country of study—US	0.805^** (0.352)	0.099; 1.511	0.785^** (0.334)	0.115; 1.454	0.805^** (0.386)	0.011; 1.599	0.785^** (0.353)	0.058; 1.511	0.805 [0.146]	0.189; 1.487	0.785^* [0.088]	0.225; 1.397
Animal products	1.056^*** (0.358)	0.339; 1.774	1.025^*** (0.352)	0.318; 1.732	1.056^*** (0.402)	0.230; 1.883	1.025^** (0.402)	0.198; 1.852	1.056^** [0.028]	0.402; 1.777	1.025^** [0.026]	0.361; 1.734
Processed products	1.415^*** (0.534)	0.344; 2.485	1.547^*** (0.538)	0.468; 2.625	1.415^** (0.575)	0.233; 2.596	1.547^*** (0.563)	0.389;2.704	1.415^* [0.076]	0.453; 2.359	1.547^* [0.052]	0.623; 2.505
Local def.–state grown	0.095 (0.403)	-0.713; 0.902	0.068 (0.394)	-0.723; 0.859	0.095 (0.494)	-0.921; 1.111	0.068 (0.475)	-0.907; 1.044	0.095 [0.876]	-0.713; 0.912	0.068 [0.918]	-0.712 0.841
Local def.–specific region	-0.042 (0.245)	-0.554; 0.450	0.012 (0.230)	-0.449; 0.472	-0.042 (0.229)	-0.513; 0.430	0.012 (0.215)	-0.429; 0.453	-0.042 [0.906]	-0.426; 0.345	0.012 [0.924]	-0.361; 0.378
Local def.–general	-0.079 (0.481)	-1.043; 0.886	-0.238 (0.488)	-1.216; 0.740	-0.079 (0.609)	-1.330; 1.173	-0.238 (0.615)	-1.501; 1.026	-0.079 [0.978]	-1.096; 0.963	-0.238 [0.798]	-1.278; 0.789
Method—choice experiment	2.139^*** (0.733)	0.669; 3.608	2.007^*** (0.727)	0.551; -3.464	2.139^*** (0.764)	0.569; 3.709	2.007^*** (0.737)	0.493; 3.522	2.139^** [0.060]	0.925; 3.446	2.007^* [0.064]	0.854; 3.246
Hypothetical experiment	-0.344 (0.434)	-1.215; 0.527	-0.443 (0.421)	-1.287; 0.401	-0.344 (0.463)	-1.295; 0.607	-0.443 (0.430)	-1.326; 0.440	-0.344 [0.484]	-1.113; 0.474	-0.443 [0.308]	-1.122; 0.316
Participants’ origin—shoppers	-0.334 (0.374)	-1.084; 0.417	-0.583 (0.383)	-1.351; 0.185	-0.334 (0.414)	-1.185; 0.517	-0.583 (0.410)	-1.427; 0.260	-0.334 [0.538]	-1.025; 0.338	-0.583 [0.246]	-1.291; 0.079
Number of attributes	-0.257 (0.188)	-0.634; 0.120	-0.131 (0.173)	-0.477; 0.215	-0.257 (0.196)	-0.659; 0.145	-0.131 (0.181)	-0.502; 0.240	-0.257 [0.308]	-0.598; 0.071	-0.131 [0.532]	-0.452; 0.179
Age	-0.064 (0.040)	-0.144; 0.015	-0.052 (0.039)	-0.130; 0.026	-0.064 (0.041)	-0.149; 0.020	-0.052 (0.040)	-0.133; 0.030	-0.064 [0.296]	-0.136; 0.006	-0.052 [0.338]	-0.120; 0.017
Gender	-0.035^* (0.019)	-0.072; 0.024	-0.038^** (0.018)	-0.074; 0.002	-0.035^* (0.021)	-0.077; 0.008	-0.038^** (0.019)	-0.077; 0.001	-0.035 [0.182]	-0.070; 0.000	-0.038^* [0.010]	-0.071; -0.006
obs	69		69		69		69		69		69
F	3.940		5.030		4.670		6.480
Prob >F	0.000		0.000		0.000		0.000
R²	0.386		0.413		0.386		0.413		0.386		0.413
Adj, R²	0.227		0.260		0.227		0.260		0.227		0.260

Note: Dependent variable is WTP for local; Standard errors in parentheses; p-values in brackets. CI refers to 95% confidence interval.

***, **, * indicate significance at the 1%, 5%, and 10%-level, respectively. sqrt(n) is used as weight.