Table 1 Mixed-effects models for treatment and time fixed effects
From: Mobilising climate action with moral appeals in a smartphone-based 8-week field experiment
Outcome variable | Best model | LRT | FE (treatment) | FE (time– date) | FE (interaction) |
|---|---|---|---|---|---|
Log carbon footprint overall | Mixed effect model (random intercept) with interaction between time and treatment fixed effect | base: 490.83, p < 0.001 with time FE only: 23.709, p < 0.001 | 0.145 (−0.12, 0.42) | 0.018 (0.016, 0.02) | −0.006 (−0.009, −0.004) |
Heating carbon footprint | Mixed effect model (random intercept, treatment random slope), with interaction between time and treatment fixed effect | base: 728.19, p < 0.001 no interaction: 11.07, p = 0.001 no random slope: 25.11, p < 0.001 | −4.148 (−13.9, 6.77) | 0.444 (0.40, 0.49) | −0.098 (−0.15, −0.04) |
Food carbon footprint | Mixed effect model (random intercept, treatment random slope), with interaction between time and treatment fixed effect | base: 32.568, p < 0.001 no interaction: 6.4963, p = 0.039a, no random slope: 25.884, p < 0.001 | 1.578 (−0.89, 3.82) | 0.029 (0.006, 0.05) | −0.031 (−0.06, 0.004) |
Consumption carbon footprint | Mixed effect model (random intercept, treatment random slope), treatment & time fixed effects | base: 20.9, p = 0.0003 no time FE: 9.28, p = 0.002 | −1.04 (−3.08, 1.07) | 0.063 (0.02, 0.10) | NA |
Electricity carbon footprint | Mixed effect model (random intercept), time fixed effect | base: 120, p < 0.001 | NA | 0.007 (0.006, 0.01) | NA |
Carbon footprint from flying | Base model (random intercept) | NA | NA | NA | NA |
Car carbon footprint | Mixed effect Model (random intercept, treatment random slope), treatment fixed effect | base: 68.484, p < 0.001 no random slope: 64.135, p < 0.001 | 4.670 (0.55, 9.10) | NA | NA |
Civic climate positivity score | Zero-inflated Poisson mixed effect model (random intercept), treatment & time fixed effects, time fixed effect for excess zeros | base: 67.65, p < 0.001 with random slope no time FE: 56.36, p < 0.001 | 0.293 (0.04, 0.55) | 0.008 (0.006, 0.01) zero-part coefficient: 0.003 | NA |
