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. 2016 Sep 1;4:e2237. doi: 10.7717/peerj.2237

Table 2. Mixed models testing the interaction between carotenoid treatment and time.

The reported tests are the best fitted models with an interaction at P < 0.10, or instead, when it is removed at higher P-values by following a backward-step wise procedure (see Methods).

Dependent variable Terms in the model Slope SE F df P
Eye rings redness Carotenoid 10.22 3,167 <0.001
Sex 3.97 1,167 0.048
Time 5.43 2,237 0.005
Carotenoid × time 2.65 6,237 0.017
Eggs −0.001 0.001 5.05 1,237 0.026
Total brightness −0.0001 0.0001 18.05 1,237 <0.001
Plasma tocopherol 0.026 0.009 7.98 1,237 0.005
Bill redness Carotenoid 6.58 3,168 <0.001
Time 8.64 3,235 <0.001
Carotenoid × time 1.96 6,235 0.072
Eggs −0.001 0.001 5.87 1,235 0.016
Total brightness −0.0002 0.00002 63.68 1,235 <0.001
Plasma tocopherol 0.033 0.011 9.23 1,235 0.003
Legs redness Carotenoid 6.04 3,167 <0.001
Sex 17.6 1,167 <0.001
Time 12.44 2,227 <0.001
Sex × time 1.36 2,227 0.258
Carotenoid × time 0.63 6,227 0.703
Eggs −0.025 0.022 1.28 1,227 0.259
Red chip 1.251 0.274 20.85 1,227 <0.001
Plasma tocopherol 1.129 0.467 5.84 1,227 0.017
Plasma retinol −1.854 1.147 2.61 1,227 0.108
Plasma lutein Carotenoid 105.1 3,164 <0.001
Sex 54.22 1,164 <0.001
Time 69.61 2,237 <0.001
Sex × carotenoid 5.22 3,164 0.002
Carotenoid × time 36.81 6,237 <0.001
Plasma tocopherol 0.456 0.026 313.86 1,237 <0.001
Plasma retinol 0.168 0.065 6.74 1,237 0.01
Eggs −0.004 0.001 8.57 1,237 0.004
Plasma zeaxanthin Carotenoid 309.6 3,164 <0.001
Sex 47.35 1,164 <0.001
Time 73.54 2,235 <0.001
Carotenoid × time 95.93 6,235 <0.001
Sex × carotenoid 3.68 3,164 0.013
Sex × time 4.4 2,235 0.013
Plasma tocopherol 0.379 0.026 216.34 1,235 <0.001
Plasma retinol 0.188 0.064 8.72 1,235 0.004
Eggs −0.006 0.001 20.9 1,235 <0.001
Plasma tocopherol Carotenoid 2.61 3,167 0.053
Sex 2.56 1,167 0.112
Time 117.68 2,236 <0.001
Carotenoid × time 2.63 6,236 0.017
Sex × time 4.89 2,236 0.008
Plasma retinol 0.548 0.122 20.25 1,236 <0.001
Eggs −0.009 0.002 14.94 1,236 <0.001
Plasma retinol Carotenoid 2.11 3,168 0.101
Time 36.06 2,238 <0.001
Carotenoid × time 1.01 6,238 0.421
Plasma tocopherol 0.0852 0.019 20.8 1,238 <0.001
Eggs −0.002 0.001 5.14 1,238 0.024
UA & ALB-corrected PLAOX Carotenoid 7.19 3,164 <0.001
Time 0.38 2,187 0.686
Carotenoid × time 2.57 6,187 0.021
Uric acid 0.768 0.053 2.14 1,187 <0.001
Albumin −0.498 0.112 19.99 1,187 <0.001
Plasma retinol 0.228 0.098 5.17 1,187 0.024
Plasma TRG-corrected MDA Carotenoid 1.05 3,164 0.371
Sex 0.29 1,164 0.593
Time 14.43 2,228 <0.001
Carotenoid × time 0.71 6,228 0.645
Sex × carotenoid 1.8 3,164 0.149
Sex × time 0.78 2,228 0.46
Plasma tocopherol −0.04 0.045 0.81 1,228 0.37
Plasma retinol −0.089 0.108 0.67 1,228 0.413
Plasma triglycerides 0.298 0.031 90.13 1,228 <0.001
Eggs 0.001 0.002 0.37 1,228 0.543
Resistance to oxidative stress in erythrocytes Carotenoid 1.48 3,163 0.223
Sex 1.3 1,163 0.256
Time 1.7 2,203 0.185
Carotenoid × time 0.69 6,203 0.657
Sex × carotenoid 0.59 3,163 0.619
Plasma retinol −20.202 8.811 5.26 1,203 0.023
Eggs −0.339 0.18 3.55 1,203 0.061
Lag time −0.122 0.021 35.9 1,203 <0.001

Note:

ALB, albumin; MDA, malondyaldehydes; PLAOX, plasma antioxidants; TRG, tryglycerides; UA, uric acid.