Incentive Conditioning Study Proposal

APPENDIX H

Incentive Conditioning Study Proposal

Incentive Conditioning Study Proposal
Description: In the 2010 NSCG new cohort data collection effort, a sample of cases identified as
hard to enumerate cases had not responded to the 2010 NSCG after numerous contact attempts.
These cases were of high analytical interest to the NSCG because they tended to have large
sampling weights and tended to include a large proportion of minority cases.
To encourage response among these cases, we conducted an incentive study to examine the impact
of a $20 and $30 incentive against a control group that receive additional contacts but no incentive.
As expected, the use of the incentive led to an increase in response for these hard to enumerate
cases. Final responses rates for the cases included in the late-stage incentive were 6.4% for the
control group, 24.1% for the $20 incentive treatment group, and 29.5% for the $30 incentive group.
In addition to the late-stage incentive used in the 2010 NSCG, all cases in the 2010 NSRCG were
offered an incentive contingent on their completion of the survey.
As we consider the plans for interviewing these previously incentivized cases in the 2013 NSCG
survey cycle, questions exist about whether these cases require an incentive to respond in future
survey cycles. To answer these questions we propose an incentive conditioning study as part of the
2013 data collection processing. The 2013 NSCG incentive conditioning study will include cases
that received an incentive in the 2010 survey cycle and responded to the survey. These cases will
be randomly allocated to three treatment groups as part of the 2013 NSCG data collection effort:
•

No incentive

•

Incentive offered at the beginning of data collection

•

Incentive offered at a late stage of data collection

Research Questions: This study is designed to provide insight on the following questions:
•

Do previous incentive recipients require an incentive to encourage response in future survey
cycles?

•

Demographically, how do the following groups differ:
o Previous incentive recipients that responded in a future survey cycle without an
incentive
o Previous incentive recipients that responded in a future survey cycle with an early
incentive
o Previous incentive recipients that responded in a future survey cycle with a late stage
incentive

•

Using the information gathered in the evaluation of demographic differences, what data
collection strategy could be used in future survey cycles to optimize bias reduction for
previously incentivized cases?

•

If an incentive is required in future survey cycles for previous incentive recipients, what is
the optimal strategy for the offering of the incentive? Optimal should be measured in terms
of response, bias, timing, and cost.

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Eligibility, Treatment Groups, and Sample Size: Although these two incentivized populations
(2010 NSCG hard to enumerate cases and 2010 NSRCG cases) will follow the same incentive data
collection methodology, the selection of the incentive conditioning sample for each population and
the evaluation of the study results will be conducted independently. Each group will be randomly
allocated into one of three treatment groups: no incentive, early incentive, late-stage incentive. The
incentive for this study will be a $30 prepaid debit card incentive that is similar to the debit card
incentive used in the 2010 NSCG survey cycle. These debit cards will have a 6 month usage period
at which time the cards will expire and the unused funds will be returned to Census and NSF (minus
the predetermined per card fee).
In the 2010 NSCG incentive study, there were approximately 1,000 cases that responded to the
survey after receiving a late stage incentive. All the cases in this group (which are part of the 2013
NSCG old cohort) with a valid address will be eligible for the 2013 NSCG incentive conditioning
study. The eligible cases will be randomly allocated across the three treatment groups with each
group being allocated the approximately same sample size (n = 333 for each group). For the 13,000
cases from the 2010 NSRCG sample that will be part of the 2013 NSCG sample, we will randomly
allocated the cases across the three treatment group with each group being allocated approximately
the same sample size (n = 4,333 for each group).
Additional Methodology/Implementation Information: Since both $20 and $30 incentives were
offered in the 2010 NSCG incentive study, we will only use $30 incentives in this incentive
conditioning study to avoid any adverse impact associated with offering a lower amount than
offered in the 2010 survey cycle.
The cases included in this study will follow the data collection pathway of the corresponding
treatment groups in the 2013 NSCG incentive study proposed for the 2013 NSCG new cohort cases.
The additional data collection cost associated with this study has a maximum value of $325,000
($30 incentive + $5 per card processing fee for 667 cases from the 2010 NSCG and 8,667 cases
from the 2010 NSRCG that could receive an incentive). However, please note that the groups that
are offered an incentive at a later stage will not require an incentive be sent to all cases since some
cases will response in an earlier data collection phase prior to the incentive being offered.
Furthermore, please note that any unused funds associated with the incentive debit cards will be
returned to Census and NSF.

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