I'm designing an incentive experiment for a survey of teen respondents. I'm wondering what amount of incentive will work for a short phone survey. The incentive will be promised (rather than pre-paid) because we recruit teens once their parent has been interviewed, and it's all done on the phone (an RDD survey). I've found a lot of research on incentives with adults, incentives with kids/teens in school/medical settings, but not a lot on incentives with teens on the phone. We might offer this incentive in cash and/or a gift card. Thanks in advance for findings or advice. The survey is ongoing so we already have a parental permission protocol, etc.