Table 1.

Relative effectiveness of recruitment strategies according to cost (per participant) and enrolment yields

	Lower costa	Higher costa
Upper thirdb	Community-focused strategies: ▪Posters	Kindergarten: ▪Phone contacts
Middle thirdb	Media: ▪Internet
Lower thirdb	Media: ▪Newspapers, Radio Community-focused strategies: ▪Recommendations Health professionals	Community-focused strategies: ▪Flyers ▪Advertisement on public transport ▪Face-to-face recruitment at public festivals, at clinic, city center/shopping center Kindergarten: ▪Email contacts

^aMedian cost of €23.33 divides the strategies into lower and higher cost portions based on whether the estimated cost was below/equal or above the median

^bRanking of relative effectiveness is divided into upper (3.80–5.70% enrolled families), middle (1.90–3.79% enrolled families), and lower (<1.89 enrolled families) thirds. ▪/•Subcategories are named if there were differences in cost and relative effectiveness in a main strategy