Table 2.
News feed advertising details and costs by subgroups.
| Recruitment metric | Gendera | Age (years) | Time relative to the pandemic | Day of the week | ||||||||
|
|
Men | Women | 18-34 | 35-64 | Before | During | Weekday | Weekend | ||||
| Facebook costs | ||||||||||||
|
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Estimated target audience, n | 6300 | 11,700 | 4400 | 13,700 | 17,900 | 17,900 | 17,900 | 17,900 | |||
|
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Money spent, US $ | 192.22 | 134.95 | 28.60 | 306.84 | 131.34 | 197.51 | 191.43 | 143.36 | |||
|
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Impressions, n | 18,655 | 9521 | 3264 | 23,872 | 8313 | 19,961 | 17,086 | 11,730 | |||
|
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Cost per impression, US $ | 0.010 | 0.014 | 0.009 | 0.013 | 0.016 | 0.010 | 0.011 | 0.012 | |||
|
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Unique viewers, n | 6765 | 4924 | 1331 | 9652 | 3165 | 8573 | N/Ab | N/A | |||
|
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Cost per unique viewer attracted, US $ | 0.028 | 0.027 | 0.021 | 0.032 | 0.041 | 0.023 | N/A | N/A | |||
|
|
Clickers, n (% of unique viewers) | 116 (1.7) | 156 (3.2)c | 32 (2.4) | 242 (2.5) | 116 (3.7)c | 158 (1.8) | 165d | 113d | |||
|
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Cost per click attracted, US $ | 1.66 | 0.97 | 0.89 | 1.34 | 1.13 | 1.25 | 1.16 | 1.27 | |||
|
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Completers of webform, n (% of clickers)e | 14 (12.1) | 18 (11.5) | 7 (21.9) | 25 (10.3) | 11 (9.5) | 21 (13.3) | 15 (9.1) | 17 (15.0) | |||
|
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Responsive volunteers, n (% of clickers)f | 9 (7.8) | 11 (7.1) | 3 (9.4) | 17 (7.0) | 10 (8.6) | 10 (6.3) | 7 (4.2) | 11 (9.7) | |||
|
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Cost per responsive volunteer attracted, US $ | 21.36 | 12.27 | 9.53 | 18.05 | 13.13 | 19.75 | 31.08 | 15.88 | |||
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Eligible volunteers, n (% of responsive volunteers)g | 4 (44.4) | 4 (36.4) | 1 (33.3) | 7 (41.2) | 5 (50.0) | 3 (30.0) | 4 (57.1) | 4 (36.4) | |||
|
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Cost per eligible volunteer attracted, US $ | 48.06 | 33.74 | 28.60 | 43.83 | 26.27 | 65.84 | 47.86 | 35.84 | |||
| Other costs, US $ | ||||||||||||
|
|
Start-uph | 94.88 | 94.88 | 94.88 | 94.88 | 94.88 | 94.88 | 94.88 | 94.88 | |||
|
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Contacting webform completers | 37.80 | 48.60 | 18.90 | 67.50 | 29.70 | 56.70 | 40.50 | 45.90 | |||
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Screening responsive volunteers for eligibility | 72.90 | 89.10 | 24.30 | 137.70 | 81.00 | 81.00 | 56.70 | 89.10 | |||
| Total costs: cost per eligible volunteer enrolled, US $ | 99.45 | 91.88 | 166.68 | 86.70 | 67.38 | 143.36 | 95.88 | 93.31 | ||||
aExcludes viewers with uncategorized gender (43/11,738, 0.4%); 2 out of these 43 viewers (4.7%) clicked the advertisement and 0 volunteered for the study.
bN/A: not applicable; this value was not traceable.
cHigher for women vs men (χ21=25.9, P<.001) and before vs during pandemic (χ21=32.9, P<.001), but not different by age (χ21=0.02, P=.89).
dThe percentage cannot be calculated because the number of unique viewers (ie, the denominator) was not traceable.
eNot different by any of the categories (gender: χ21<0.001, P>.99; age: χ21=2.6, P=.11; time: χ21=0.6, P=.44; weekday vs weekend: χ21=1.8, P=.18).
fProportion of clickers volunteering (called conversion in the literature). It was not different by any of the categories (gender: χ21<0.001, P>.99; age: Barnard test P=.89; time: Barnard test P=.60; weekday vs weekend: χ21=2.5, P=.11).
gNot different by any of the categories (gender: Barnard test P=.79; age: Barnard test P=.91; time: Barnard test P=.43; weekday vs weekend: Barnard test P=.53).
hStart-up costs (Table 1) covered all participants, so were divided evenly between the two categories of each comparison.