J Incentives Response Rates NR Bias

APPENDIX J. INCENTIVES, RESPONSE RATES AND NONRESPONSE BIAS

Research unequivocally demonstrates that incentives increase response rates and reduce nonresponse bias. Singer and Ye¹ completed a systematic review of articles appearing since 2002 on the use of incentives to enhance response rates. They found that: (a) incentives increase response rates for all modes of survey administration; (b) higher incentive amounts increase response rates more than lower amounts; and (c) monetary incentives were more effective than gifts; and (d) prepaid incentives are generally more effective than promised incentives on survey participation. In a review of incentives for establishment surveys,² Cook et al. found the similar effects when the survey respondent represents an organization.

Leverage-salience theory posits that incentives increase how positively a sample member perceives the survey request (that is, the incentives exert positive leverage). The positive leverage increases the likelihood of participation, especially among individuals for whom other attributes of the survey have low salience, such as the topic or contact strategy.³ Incentives can also encourage participation because of the norm of reciprocity—a person who receives a gift may be more motivated to comply with an associated request.⁴

Incentive Amounts and Response Rates. There has been extensive experimental research on the relative effectiveness of different incentive amounts. Higher incentive amounts increase response rates, although the relationship between incentive amounts and response rates is not linear.⁵ The U.S. Census Bureau has experimented with incentives on the Survey of Income and Program Participation since 1996. The most recent experiment conducted in 2014 compared results of postpaid $10, $20, and $40 incentive amounts to those of a $0 control group.⁶ Overall, the $20 incentive increased response rates compared to the control group, and the $40 incentive increased response rates compared to both the control group and the $20 incentive. In addition, these findings held for the subgroup of low income respondents. Among low income respondents, the response rates were 71 percent, 73 percent, and 77 percent for the $0, $20, and $40 groups, respectively. The National Survey of Family Growth included an incentive experiment that compared a $20 payment to a $40 payment. The response rate for those offered $20 was 62 percent, and for those offered $40, it was 72 percent. Those receiving the higher amount were also less likely to express objections or reluctance to the interview than those receiving $20.⁷ The Medical Expenditures Panel Study included an incentive experiment that included $30, $50, and $70 incentive amounts. The results across the full sample showed that the composite response rate across all five rounds of data collection was higher for both the $50 and $70 respondent payment group relative to the $30 group. In addition, the difference in response rates between the $70 and $50 respondent payment groups was also statistically significant, with a composite response rate of 71 and 67 percent for the $70 and $50 groups, respectively.⁸ The National Survey of Household Drug Use included an experiment to compare the impact of $20 and $40 incentive treatments with a $0 control on measures of respondent cooperation, data quality, survey costs, and population substance use estimates. Overall, the $40 incentive resulted in a significantly higher response rate than the $20 incentive (83 versus 79 percent), and the $20 incentive resulted in a significantly higher response rate than the $0 control (79 versus 69 percent).⁹ In a nationally-representative survey of public school principals, Coopersmith et al. tested several different incentive strategies, including higher incentives for early response, and a combination of pre- and post-paid incentives. ¹⁰ Their findings suggest that a substantial postpaid incentive, of $50 for a 15-minute survey, was the most effective to promoting response rates.

Incentives for Complex Data Collections. For complex and burdensome data collections, incentives can be used to both maximize response rates and encourage continued participation through multiple study activities. The National Household Food Acquisition and Purchase Survey offered incentives for participating in recruitment and multiple data collection touchpoints during the course of a week-long survey. In a field test of incentive amounts, results showed that providing a larger incentive improved response rates. The response rate for households in the “high incentive” group ($100 base incentive) was nine percentage points higher than the “low incentive” group ($50 base incentive).¹¹ These findings provided justification for an incentive of $100 for the full study (OMB Control Number 0536-0068, expired 3/31/2015).

Incentives and Nonresponse Bias. Several studies have also found that the use of incentives is effective at changing the composition of the sample and potentially reducing nonresponse bias. Offering incentives can increase participation among low-income respondents and those who are less interested in the research.^12,13 For example, Singer et al. found that a $5 prepaid incentive brought a disproportionate number of low-education respondents into the sample.¹⁴ Groves et al. found that while individuals more involved in their community were more likely to respond to a survey about issues facing the community, offering a $5 prepaid incentive increased response among those who were not involved in their community.¹⁵ The incentive increased the response rate in the “low community involvement” group by 42 percentage points and in the “high community involvement” group by 16 percentage points. This suggests that without the incentive, the sample would be biased toward individuals who were more interested in the topic and estimates of community involvement from the survey would be biased upward.

Respondent Incentives for NSFS. Below we describe the rationale for incentives proposed for NSFS, which are summarized in Supporting Statement A, Table A9.1. The proposed incentives balance encouraging cooperation (and thus reducing nonresponse bias) and using project resources efficiently, and are appropriate given the burden to participate in the multiple data collection activities needed to address the analytical objectives of the study. Table T1 summarizes a selection of incentives that OMB has approved for populations and activities that are similar to those in NSFS.

SFA directors/business managers. SFA staff cooperation with multiple data collection activities is necessary to obtain nationally representative data to address Objectives 1, 3, and 5 (Supporting Statement A, Table A.1): (1) the SFA Director Survey (Appendix F03.01), which will take an average of 0.75 to 1.5 hours to complete depending on the sample group; (2) the Quarterly Food Purchase Data request (Appendix F01.01), which will take approximately six hours to complete; (3) the SFA On-Site Cost Interview (Appendix F05.02), which will take approximately three hours to complete; and (4) the SFA Follow-Up Cost Interview, which will take approximately two hours to complete. These activities require respondents to compile and report information from multiple sources, such as policy documents, food purchase and personnel records, and financial statements. Participants asked to complete the Quarterly Food Purchase Data request (Appendix F01.01) will also be invited to attend a training webinar (Appendix C15) to help them understand the detailed records that are needed and the submission process. The proposed incentives for these activities range from $35 to $275 and reflect the time needed to participate and the cost of respondents’ time based on average wages (Table A9.1). For especially burdensome activities, such as the Quarterly Food Purchase Data request, the incentive does not fully reflect the amount of time for participation because local school district rules might prohibit staff from accepting larger incentives.

SNMs. SNMs will be asked to provide data to address Objectives 2, 3, 4, and 6 (Supporting Statement A, Table A.1). The most burdensome activity for SNMs—the Menu Survey (Appendix F02.01)—requires significant time and flexibility beyond SNMs’ normal job responsibilities. It is estimated to take nine hours to complete the survey, including time for training, technical assistance, and data retrieval. The need for training and technical assistance speaks to the complexity of completing the survey and the high burden on respondents. Without complete data from the Menu Survey, the study will not be able to address core objectives of the SNMCS-II study component: to determine the food and nutrient content of school meals and their nutritional quality, the cost of producing the meals, and students’ plate waste. Similarly, the study will not be able to estimate the cost of producing the meals in each outlying area. The Menu Survey will be completed over several consecutive days, which requires SNMs to find time to complete it in addition to their job responsibilities. SNMs will receive a prepaid incentive of $75 and an additional $150 after we have verified that they have provided complete data (Table A9.1). Prepaid incentives for self-administered establishment surveys like the Menu Survey have been shown to increase response rates more than promised incentives alone and can be more effective than even a promised incentive with a higher value.¹⁶ The post-paid incentive is designed to improve data quality and reduce nonresponse bias and data collection costs by motivating SNMs to provide complete data and, if needed, to quickly respond to requests for clarification after they submit the survey.

SNMs in Groups 3 and outlying areas (parts of the SNMCS-II component) will also be asked to complete the SNM Cost Interview (Appendix F05.10) to address Objective 3, which requires them to compile labor and wage information for kitchen staff, complete the interview, and track down any missing data. SNMs in the FFVP evaluation component will be asked to complete the web-based FFVP SNM Survey to address Objective 6 (Appendix F04.02). The proposed incentives ($50 for the SNM Cost Interview and $25 for the FFVP SNM Survey) are commensurate with the time needed to participate and the cost of respondents’ time based on SNMs’ average wages.

Principals. Principals in Groups 3 and outlying areas (parts of the SNMCS-II component) will be asked to complete the Principal Cost Interview to address Objective 3 (Appendix F05.12). They will be asked to compile and report labor and wage information for non-food service staff in the school who help with food service activities such as distributing applications for free/reduced-price meals. They will also be asked to provide any data that were not available during the interview. The effort is estimated to take 45 minutes, and the proposed $40 incentive reflects the needed time and principals’ average wages.

School liaisons. School liaisons are the linchpin for successfully recruiting students and parents in Group 2a and 2b schools in the SNMCS-II and FFVP evaluation components and coordinating data collection activities at the schools. These liaisons, typically administrators or other school staff, play an essential role in student and parent recruitment and obtaining consent. Because studies have found that rates of active consent were lower among disadvantaged schools,^17,18 liaisons’ aid is critical to minimizing nonresponse bias by providing student and parent contact information and guidance about the most effective means of communicating and obtaining consent. Liaisons will also coordinate in-school data collection activities, including distributing reminders to selected students and escorting students to and from the area where Student Interviews and Dietary Recall Interviews will be conducted. Because completing these study-related responsibilities in addition to regular job responsibilities may require time outside of normal working hours, the stipend is designed to offset financial burden such as childcare expenses. In schools that use passive consent, liaisons will receive a stipend of $105 ($45 before the target week plus $60 after). In schools that use active consent, liaisons may be asked to follow up directly with students and parents who have not responded; they will receive a stipend of $150 to recognize the additional work ($90 before the target week plus $60 after). The proposed amounts are commensurate with the amount of time school liaisons will spend supporting the study and reflect average wages for Educational Instruction and Library Occupations (https://www.bls.gov/oes/current/oes_nat.htm).

Students and parents. Student and parent data collection is essential to answering research questions for Objectives 4 and 6 in the SNMCS-II and FFVP evaluation components, respectively (Supporting Statement A, Table A.1). Students will be selected randomly for the study and will include those who participate in school meals programs and those who do not. Because topic salience is a driver of survey participation,¹⁹ the study will be less salient to students (and their parents) with little or no school meals participation, and they will have less motivation to participate. The proposed incentives are designed to increase representativeness by encouraging participation among those who might otherwise ignore the study. The amounts are commensurate with those in SNMCS-I and were approved for SNMCS-II. The exception is elementary school parents; their proposed incentives are less than the amounts approved for SNMCS-I because NSFS offers parents the option of completing the parent-assisted portion of the dietary recall in-person or by telephone. The telephone option is less burdensome. The proposed amounts are also similar to the $25 post-payment incentive that OMB approved for respondents who completed the web-based Parent Survey for the Project LAUNCH Cross-Site Evaluation (OMB Control Number 0970-0373, expired 10/31/2019) after data collection had started. Following the addition of incentives, it was found that completion rates and representativeness of respondents both improved, relative to no incentive early in data collection.^20,21

Experiments testing the use of incentives in telephone surveys of the general adult population, similar to the parents included in this study, support the use of a promised incentive to improve response rates.^22,23,24 Brick et al. observed a dramatic effect in their experiment comparing $10 and $5 incentives. The response rate for the $10 group was 26 percent compared with 19 percent for the $5 group. In their 2015 meta-analysis of monetary incentives and response rates in household surveys, Mercer et al. noted the variability in the effectiveness of incentives across experiments. However, across the studies included in the meta-analysis, the authors concluded that promised incentives in the range of $15 to $30 could be expected to raise telephone survey response rates 6 to 7 percentage points compared to no incentives.

Table T1. Selected projects and incentives similar to NSFS

Project name, OMB control number, and expiration date	Estimated burden	Description of data collection	Approved incentives	Relevance to NSFS data collection
SFPS-III 0584-0471 (Expired 3/31/2012)	12.5 hours	Participating SFAs were paid for providing the paperwork documenting their food procurement.	$100-$400 per SFA	SFA directors participating in the SFPS-IV component of the study will receive incentives totaling up to $350, which is in the range of incentives for SFPS-III. However, the payments are divided so that respondents receive an incentive after completing key activities. SFA directors will receive $275 for Quarterly Food Purchase Data plus $60 for SFPS SFA Director Survey; or $275 for Quarterly Food Purchase Data plus $75 for SNMCS+SFPS SFA Director Survey.
SNMCS-II 0584-0648 (Expired 9/30/2022)	15 minutes to assist with student 24-hour dietary recall; 25 minutes for Parent Interview	Parents of elementary students assisted their children with completing a 24-hour dietary recall. Parents of elementary, middle, and high school students completed the Parent Interview. A subsample of parents of elementary students were selected to complete a second parent-assisted dietary recall with their children.	$25 for parents of elementary students; $15 for parents of middle/high school students	The incentive amounts and burden are the same as the amounts proposed for the SNMCS-II component of the study. Parents who complete the second parent-assisted dietary recall will receive a second incentive of the same amount.
SNMCS-II 0584-0648 (Expired 9/30/2022)	40-55 minutes for dietary recall (depending on student age); 10 minutes for Student Interview	Elementary students completed a Student Interview plus the parent-assisted 24-hour dietary recall. Middle and high school students completed both the Student Interview and 24-hour dietary recall on their own, without parent assistance. Because the time period for the middle/high school student recall is the day before the interview, in some cases students were interviewed on a Saturday to capture Friday intakes. A subsample of middle and high school students were selected to complete a second dietary recall.	$5 for elementary students; $15 for middle/high school students (weekdays) or $20 (Saturdays)	The incentive amounts and burden are the same amounts proposed for the SNMCS-II component of the study. Middle and high school students who complete the second dietary recall will receive a second incentive of the same amount. Students in the FFVP sample will complete the in-school dietary recall without parent assistance, similar to how middle/high school students in the SNMCS-II component. They will receive a $15 incentive.
SNMCS-II 0584-0648 (Expired 9/30/2022)	8-10 hours	SNMs completed the Menu Survey, providing detailed information about school meals for several consecutive days over the course of a designated target week.	Up to $100 ($75 pre-pay plus $25 data retrieval)	In recognition of the extensive burden to complete this key instrument for the SNMCS-II study component, and to incentivize the data retrieval step to promote data quality, NSFS proposes an increase to a maximum of $225 ($75 pre-pay/$150 post-pay) to SNMs completing the Menu Survey.
SNMCS-II 0584-0648 (Expired 9/30/2022)		School liaisons provided guidance to the study team about the most effective means of communicating with students and parents, student and parent contact information, and critical planning information for on-site data collection. Liaisons coordinated in-school data collection activities, including distribution of consent forms and reminders to selected students. Depending on district requirements, schools used either a passive (opt-out) process for consent or an active consent process. For the latter, liaisons were asked to follow up directly with students and parents who had not responded.	Passive consent process: $65 ($30 gift card before the target week plus $35 gift card after). Active consent process: $95 ($60 gift card before the target week plus $35 gift card after).	Proposed incentives are higher for the current study because of the important role that school liaisons play in student and parent recruitment and data collection, and the potential that schools are continuing to face staffing challenges. For the SNMCS-II and FFVP study components, passive consent school liaisons will receive $105 total ($45 before the target week plus $60 after). In active consent schools, they will receive $150 total ($90 before the target week plus $60 after).
Middle Grades Longitudinal Study of 2017-18 (MGLS:2017) Operational Field Test (OFT) and Recruitment for Main Study Base-year 1850-0911 (Expired 12/31/2019)		School coordinators coordinated logistics with the data collection contractor; compiled and supplied to the contractor a list of eligible students for sampling; communicated with teachers, students, and parents about the study to encourage their participation; distributed and collected consent forms; and assisted the test administrator in ensuring that the sampled students attended the testing sessions.	$150	The role and responsibilities and incentive amounts for NSFS school liaisons (SNMCS-II and FFVP study components) are comparable to those approved for MGLS school coordinators.
National Survey of Health Information Exchange Organizations 0955-0019 (Expires 11/30/2025)	45 minutes	Leaders of health information organizations complete screening questions to determine eligibility for the survey, and then complete the 45-minute survey.	$10 (screening questions) and $50 (survey)	The incentive amount is comparable to what administrators participating in NSFS cost data collection (SNMCS-II study component) will receive for their time. Principals will receive $40 for the 45-minute Principal Cost Interview; SFA directors will receive $150 for the 3-hour SFA On-Site Cost Interview and $90 for the 2-hour SFA Follow-Up Cost Interview.
Early Childhood Longitudinal Study, Kindergarten Class of 2023-24 (ECLS-K:2024) 1850-0750 (Expired 11/30/2022)	minutes	Teachers completed teacher-level surveys and a child-level survey for each selected child in their classroom.	$20 for teacher survey, plus $7 per child-level survey	Incentivizing teachers to participate in a survey for ECLS-K:2024 is comparable to incentivizing SNMs to participate in a survey for the FFVP study component. SNMs will receive $25 for completing the 30-minute FFVP SNM Survey.
Visual Representations for Proportional Reasoning: Impacts of a Teacher Professional Development Program for Multilingual Learners and Other Students 1850-0978 (Expires 5/31/2026)	4.5 hours	Teachers will complete three teacher measures at two points in time, and support the administration of student assessments.	$100 for completion of fall 2023 data collection, plus $225 for completion of spring 2024 data collection	OMB approved incentives for teachers in the Visual Representations project that offset the burden of participating outside of regular contracted work hours. Completing the Menu Survey for the SNMCS-II study component will similarly require SNMs to spend time outside of regular working hours responding to the data collection.
Project LAUNCH Cross-Site Evaluation 0970-0373 (Expired 10/31/2019)	30 minutes	Parents participated in the Parent Survey.	$25	The estimated burden and proposed incentives for parents participating in the SNMCS-II component are similar to the burden and incentives for the Project LAUNCH Parent Survey.

Table T2. Summary of incentive calculations

Respondent	Activity (appendices)	Calculationa	Estimated Cost	Value of proposed incentive
SFA directors	SFA Director Survey (SNMCS+SFPS) (Appendix F03.01)	Average hourly wage for SFA director is $63.83 x 1.5 hours	$95.75	$75 gift card
SFA directors	SFA Director Survey (SFPS) (Appendix F03.01)	Average hourly wage for SFA director is $63.83 x 1.25 hours	$79.79	$60 gift card
SFA directors	SFA Director Survey (SNMCS) (Appendix F03.01)	Average hourly wage for SFA director is $63.83 x 0.75 hours	$47.87	$35 gift card
SFA directors	Quarterly Food Purchase Data (Appendix F01.01)	Average hourly wage for SFA director is $63.83 x 6 hours	$412.98	$275 gift card
SFA directors/business managers	SFA On-Site Cost Interview (Appendix F05.02)	Average hourly wage for SFA director or business manager is $63.83 x 3 hours	$191.49	$150 gift card
SFA directors/business managers	SFA Follow-Up Cost Interview (Appendix F05.08)	Average hourly wage for SFA director or business manager is $63.83 x 2 hours	$127.66	$90 gift card
SNMs	Menu Survey (Appendix F02.01)	Average hourly wage for school nutrition manager is $42.92 x 9 hours	$386.28	Up to $225 gift card ($75 prepayment plus $150 data retrieval)
SNMs	SNM Cost Interview (Appendix F05.10)	Average hourly wage for school nutrition manager is $42.92 x 1.5 hours	$64.38	$50 gift card
SNMs	FFVP SNM Survey (Appendix F04.02)	Average hourly wage for school nutrition manager is $42.92 x 0.5 hours	$21.46	$25 gift card
Principals	Principal Cost Interview (Appendix F05.12)	Average hourly wage for principal is $66.10 x 0.75 hours	$49.50	$40 gift card
School liaisons	Facilitation of consent distribution and Student Interviews	Average hourly wage for school liaison is $40.45 x 2.5 hours in passive consent schools = $101.13 Average hourly wage for school liaison is $40.45 x 3.5 hours in active consent schools = $141.58	Passive consent schools: $101.13 Active consent schools: $141.58	Passive consent schools: $105 total in gift cards ($45 before the target week plus $60 after) Active consent schools: $150 total ($90 before the target week plus $60 after)
Elementary school students, SNMCS-II	Student Interview and Dietary Recall (Appendices F08.01 and F08.02)	n.a.	n.a.	$5 gift card
Elementary school students, FFVP	Student Interview and Dietary Recall (Appendices F08.01 and F08.02)	n.a.	n.a.	$15 gift card
Middle/high school students	Student Interview and Dietary Recall (Appendices F08.01 and F08.02)	n.a.	n.a.	$15 gift card (weekdays) or $20 gift card (Saturdays)b
Middle/high school students	Second Dietary Recall (Appendix F08.02)	n.a.	n.a.	$15 gift card
Elementary school parents	Parent Interview and Dietary Recall (Appendices F08.04 and F08.02)	Average hourly wage for parent: $39.58 x 0.6675 hours	$26.41	$25 gift card
Middle/high school parents	Parent Interview (Appendix F08.04)	Average hourly wage for parent: $39.58 x 0.4175 hours	$16.52	$15 gift card
Elementary school students and their parents	Second Dietary Recall (Appendix F08.02)	Average hourly wage for parent: $39.58 x 0.75 hours	$29.69	$25 gift card

n.a. = not applicable

^a Average hourly wages are from Bureau of Labor Statistics, Wages by Occupation (May 2022) (https://www.bls.gov/oes/current/oes_nat.htm) and are multiplied by 1.33 to represent fully loaded wages. The wages are SFA director or business manager (Education Administrators, All Other) = $47.99; SNMs (Food Service Managers) = $32.27; principals (Education and Childhood Administrators) = $49.70; school liaisons (Educational Instruction and Library Occupations) = $30.41; and parents (All Occupations) = $29.76. Middle/high school students were assumed not to have hourly wages. Estimated respondent burden is presented in Appendix H.

^b Approximately 12 percent of middle/high school students will be interviewed on Saturdays to measure Friday dietary intakes. These students will receive a slightly higher incentive, which helps offset transportation costs if they choose to be interviewed at a location other than home, such as a public library. Because they will need to be interviewed outside of school, there is an increased likelihood of nonresponse. The incentive is intended to reduce nonresponse bias.

1 Singer, E., and C. Ye. (2013). The Use and Effectiveness of Incentives in Surveys. Annals of the American Academy of Political and Social Science: 645 (1): 112–141.

2 Cook, S., et al. "Applying incentives to establishment surveys: A review of the literature." Proceedings of the Section on Survey Research Methods: American Statistical Association. 2009.

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4 Groves, R.M., R.B. Cialdini, and M.P. Couper. (1992). Understanding the decision to participate in a survey. Public Opinion Quarterly: 56: 475-495.

5 Mercer, A., A. Caporaso, D. Cantor, and R. Townsend (2015). How Much Gets You How Much? Monetary Incentives and Response Rates in Household Surveys. Public Opinion Quarterly: 79 (1): 105–129.

6 Westra, A., M. Sundukchi, and T. Mattingly. Designing a Multipurpose Longitudinal Incentives Experiment for the Survey of Income and Program Participation. Proceedings of the 2015 Federal Committee on Statistical Methodology (FCSM) Research Conference. 2015.

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8 Respondent Payment Experiment with MEPS Panel 13. https://meps.ahrq.gov/data_files/publications/rpe_report/rpe_report_2010.shtml

9 RTI International (2002). 2001 National Household Survey on Drug Abuse incentive experiment (prepared for the Substance Abuse and Mental Health Services Administration). Research Triangle Park, NC.

10 Coopersmith, J., L. K. Vogel, T. Bruursema, and K. Feeney. 2016. “Effects of Incentive Amount and Type of Web Survey Response Rates.” Survey Practice 9 (1). https://doi.org/10.29115/SP-2016-0002.

11 To, N. (2015).

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13 Singer, E., and R.A. Kulka. “Paying Respondents for Survey Participation.” In Studies of Welfare Populations: Data Collection and Research Issues. Panel on Data and Methods for Measuring the Effects of Changes in Social Welfare Programs, edited by Michele Ver Ploeg, Robert A. Moffitt, and Constance F. Citro. Committee on National Statistics, Division of Behavioral and Social Sciences and Education. Washington, DC: National Academy Press, 2002, pp. 105–128.

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19 Groves et al. 2006.

20 Hoard, L., and N. Deterding. “Results of Offering Incentives for a Parent Survey–Project LAUNCH Multi-Site Evaluation (OMB 0970-0373).” Memorandum to Office of Information and Regulatory Affairs (OIRA) and Office of Management and Budget (OMB), January 30, 2019.

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23 Mercer, A., A. Caporaso, D. Cantor, and R. Townsend. “How Much Gets You How Much? Monetary Incentives and Response Rates in Household Surveys.” Public Opinion Quarterly, vol. 79, no. 1, spring 2015, pp.105–129.

24 Cantor, David, Barbara O’Hare, and Kathleen O’Connor. “The Use of Monetary Incentives to Reduce Nonresponse in Random Digit Dial Telephone Surveys.” In Advances in Telephone Survey Methodology, edited by James Lepkowski, Clyde Tucker, J. Michael Brick, Edith de Leeuw, Lilli Japec, Paul Lavrakas, Michael Link, and Roberta Sangster. Wiley & Sons Publishing, 2008.