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Table 2 Results of the regression models for recipients completing the survey (including only deliverable surveys)

From: Effectiveness of incentives and follow-up on increasing survey response rates and participation in field studies

Model and test relative to intercept-only model Variable Fixed effects Variable level Completing survey
df Wald χ2 p-value p-value OR 95% CI
Model 1
χ2(6, n = 3576) = 158.793, p < 0.0001
Survey incentive 1 11.599 < 0.001 Gift card Ref   
     $2 < 0.001 2.792 1.546–5.041
Survey length 2 2.569 0.277 Short Ref   
     Medium 0.752 0.927 0.579–1.484
     Long 0.139 0.730 0.482–1.107
Follow-up waves 2 9.627 0.008 0 Ref   
     2 0.114 1.530 0.903–2.591
     3 0.005 2.121 1.250–3.597
Field study incentive 1 0.150 0.699 150 Ref   
     200 0.699 0.936 0.671–1.306
Model 2
χ2(11, n = 3576) = 162.574, p < 0.0001
Survey incentive 1 11.643 < 0.001 Gift card Ref   
     $2 < 0.001 2.798 1.550–5.054
Survey length 2 2.505 0.286 Short Ref   
     Medium 0.759 0.929 0.580–1.488
     Long 0.144 0.733 0.483–1.112
Follow-up waves 2 9.592 0.008 0 Ref   
     2 0.114 1.530 0.903–2.592
     3 0.005 2.120 1.249–3.596
Field study incentive 1 0.170 0.680 150 Ref   
     200 0.680 0.932 0.668–1.301
Noise exposure category 4 3.397 0.494 < 40 Ref   
     40–45 0.562 0.907 0.651–1.263
     45–50 0.306 0.839 0.599–1.175
     50–55 0.671 1.073 0.776–1.484
     > 55 0.594 1.093 0.787–1.519
Direction 1 1.073 0.300 West Ref   
     East 0.538 0.936 0.758–1.156
  1. All analyses excluded surveys that could not be delivered for any reason
  2. df Degrees of freedom, OR Odds Ratio, CI Confidence Interval, Ref Reference category
  3. Statistically significant (p < 0.05) results are indicated with bold typeface