Can a higher incentive increase physical 

examination response? Evidence from the National 

Health and Nutrition Examination Survey (NHANES)

Te-Ching Chen, Matt Jans, Lara Akinbami, Ryne Paulose-Ram, Damon Ogburn, David Woodwell, Allan Uribe, Jessica Graber 

2023 FCSM, Hyattsville, MD (Oct 25, 2023)

Division of Health and Nutrition Examination Surveys

National Center for Health Statistics
The findings and conclusions in this presentation are those of the 

authors and do not necessarily represent the official position of the 

Centers for Disease Control and Prevention

Disclaimer

1
Background

2
NHANES Sample Design for August 2021-August 2023

3

• Complex multistage probability sample 

design

• Selected households are screened to 

identify eligible participants

• Data are collected in screener, 

interview and physical examination
0

10

20

30

40

50

60

70

80

90

100

Response Rate

1999-2020 by 2-year cycle First Aug 2021-Aug 2023 stands

2021 PSUs before

experiment

Examined Response Rate Dropped in Early 2021/2023 cycle

Examined RR=

# oooo eeeeeeeeeeeeeeee

# oooo II II IIII II

COVID Data Collection Pause

4

Examined RR=

# oooo eeeeeeeeeeeeeeee

# oooo II II IIII II
• Exam incentive amount differed by age group. 

• SP receives interview incentive for the first time

• Exam incentives were smaller in 2021 compared with earlier cycles

NHANES Exam Incentive

0-11 years 12-15 years ≥16 years

$40 $60 $85

5
• Can a higher exam incentive increase exam response rate?

• Will it change the rate of cancelations and “no shows”? 

• Will it change the rate at which morning session participants fast 

before blood drawn?

Research Questions

6
Methods and Data

7
NHANES MEC Exam Incentive

• Incentive pilot study started in PSU 8 

0-11 years 12-15 years ≥16 years

PSU 1-7 $40 $60 $85

PSU 8+ $40 $60 $125

8
• NHANES August 2021- August 2023 cycle

• Interviewed sampled participants (SPs) aged 16 years and over

• Characteristics compared

• Demographics: race, sex, age group (16-19, 20-39, 40-59, 60+)

• Household size (1-2, 3-4, 5+)

• Interview mode (in-person, by phone)

• Health insurance status (with, without)

• General health (excellent, very good, good, fair/poor)

• Ever diagnosed diabetes (Yes, No) 

• With Interpreter (Yes, No)

• Language used during interview (English, Spanish)

Data and Method

9
• MEC examined: 

• Interviewed SP who also did MEC examination

• No appointment:

• Interviewed SP who didn’t make an appointment for MEC examination

• Cancelled: 

• Interviewed SP who made an appointment but cancelled the appointment

• No show: 

• Interviewed SP who made an appointment but didn’t show up to the MEC

MEC Examination Statuses Analyzed (Key Outcomes)

10
• Fasting sample

• All SPs aged 12 years and over examined in a morning session are 

asked to fast 8 hours before their MEC visit. 

• Did the incentive increase the compliance for SPs to 

fast for the morning session?

Fasting status before blood drawn

11
Findings

12
Overall Incentive Effect – Increases examined and 

Reduces Cancellation and “No Show”

Percent of Interviewed SPs

$85 

(PSUs 1 – 7)

$125 

(PSUs 8 – 30)

Examined 72.9% 79.5% 

No appointment 11.7% 11.1%

Cancelled/No show 15.4% 9.4%

*2-sample t-test significantly different (p< 0.05) for examined and Cancelled/No Show

13

*

*
Examined Rate for $125 Incentive PSUs is Higher Overall

79.8

74.4 75.9

70.4

62.1

69.9

75.9 73.4 71.4

78.2 79.9

74.5

78.3 81.3

85.2

78.2 79.3 82.2 80.4 77.4 74.5 75.8

87.5

82.6 81.1

84.8

79.6 78.1 80.8 79.6

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Response Rate

PSU RR Cum. Aug 2021-Aug 2023 RR

PSUs before

experiment

Experiment 

Begins!

14
0

2

4

6

8

10

12

14

DIFFERENCE (%)

: 2-sample t-test significantly different at 0.05 level CHARACTERISTICS

: difference did not reach statistical significance 

Race/Ethnicity Sex Age (years) HH Size Interview Health General Health Diabetes Interpreter Language

Mode Insurance

Difference of MEC examined rates

Difference = MEC examined % ($125 incentive) – MEC examined % ($85 incentive)

15
-12

-10

-8

-6

-4

-2

0

DIFFERENCE (%)

CHARACTERISTICS

Difference of Cancelled/No show rates

Difference = Cancelled/No show % ($125 incentive) – Cancelled/No show % ($85 incentive)

16

Race/Ethnicity Sex Age (years) HH Size Interview Health General Health Diabetes Interpreter Language

 Mode Insurance

: 2-sample t-test significantly different at 0.05 level 

 : difference did not reach statistical significance 
-4

-2

0

2

4

6

8

DIFFERENCE (%)

CHARACTERISTICS

Race/Ethnicity Sex Age (years) HH Size Interview Health General Health Diabetes Interpreter Language

Mode Insurance

Difference of No Appointment rates

Difference = No Appointment% ($125 incentive) – No Appointment % ($85 incentive)

17

: 2-sample t-test significantly different at 0.05 level 

 : difference did not reach statistical significance 
0

2

4

6

8

10

12

14

16

18

20

DIFFERENCE (%)

CHARACTERISTICS

Difference of morning sample fasting rate

Difference = morning sample fasting % ($125 incentive) – morning sample fasting % 

($85 incentive)

18

Race/Ethnicity Sex Age (years) HH Size Interview Health General Health Diabetes Interpreter Language

 Mode Insurance

: 2-sample t-test significantly different at 0.05 level 

 : difference did not reach statistical significance 
• $125 incentive reduced variability in response rates 

across demo and health characteristics

• Indicator of nonresponse bias risk reduction

• Incentive effect remains after control for person-level 

and PSU-level characteristics

Highlights of Results not Shown
• Higher incentive 

• increased examined rates

• reduced cancelled/no show rates 

• made no difference in scheduling a MEC appointment

• increased fasting rate for morning participants

• had less response rate variation among characteristics categories

Summary
• Does the incentive increase impact other rates

• Response rate for SPs younger than 16 in the same household?

• MEC Examination item response rates? 

• Models to predict/estimate size of effect among 

various groups controlling for others

Future Directions
Thank you!

Te-Ching Chen: tchen3@cdc.gov
• Health insurance status: The (first/next) questions are about health 

insurance. {Are you/Is SP} covered by health insurance or some other kind of 

health care plan? [Include health insurance obtained through employment or 

purchased directly as well as government programs like Medicare and 

Medicaid that provide medical care or help pay medical bills.]

• General health: {First/Next} I have some general questions about {your/SP's} 

health. Would you say {your/SP's} health in general is . . .(excellent, very 

good, good, fair, poor)

• Diagnosed diabetes: The next questions are about specific medical conditions. 

{Other than during pregnancy, {have you/has SP}/{Have you/Has SP}} ever 

been told by a doctor or health professional that {you have/{he/she/SP} has} 

diabetes or sugar diabetes?(Yes, No) 

Real texts of the selected questions used in this project

23
• Examined: 

• Interviewed SP who also did examination

• No appointment:

• Interviewed SP who didn’t make an appointment for MEC examination

• Cancelled: 

• Interviewed SP who made an appointment but cancelled the appointment

• No show: 

• Interviewed SP who made an appointment but didn’t show up to the MEC

Examination Statuses Analyzed (Key Outcomes)

24
• Variability in response (or nonresponse) rates across 

demographic groups is one measure of nonresponse bias 

risk

• Calculated:

– Conditional MEC response rates for several demographic and health 

groups

– Simple variance of RR values across categories of each group

• Each demographic or health variable has an RR variance 

value associated with it

Variability in response rate (RR variance) across demographic 

variables as a metric of nonresponse bias risk 

25
0

5

10

15

20

25

30

35

Overall Race Gender Age HH Size With Health

insurance

SP selfreported

general

health

Interview

Mode

Diagnosed

diabetes

Interpreter

used

Language

used in

interview

$85 incentive $125 incentive

Assessed variability in response rate (RR variance) across 

demographic variables

26
Assessed variability in RR variance across demographic 

variables (tabular results for figure on prior slide)

27

$85 incentive $125 incentive

Overall 8.7 2.7

Race 12.7 0.4

Sex 1.4 0.7

Age 22.5 2.8

HH size 4.0 0.7

Interview mode 5.6 2.0

With/Without Health Insurance 5.1 2.7

General health 1.2 3.3

Diagnosed diabetes 8.0 8.4

With/Without interpreter 33.1 13.7

Language used in interview 7.0 0.9
Assessed variability in morning sample fasting rate variance 

across demographic variables

28

$85 incentive $125 incentive

Overall 45.7 6.0

Race 132.2 5.6

Sex 10.0 0.1

Age 15.3 7.7

Interview mode 1.3 0.4

With/Without Health Insurance 0.0 0.1

General health 113.1 1.3

Diagnosed diabetes 0.3 0.3

With/Without interpreter 131.8 51.1

Language used in interview 0.5 1.7
Predicting Incentive Effect Controlling for PSU 

Characteristics

29

Fixed Random ESTIMA

TE LOWERUPPER

Incentive only 1.443 1.278 1.631

Incentive Census region, Health state, 

MEC season, Urban-rural 1.375 1.178 1.606

Incentive, gender, race, age group 1.445 1.277 1.636

Incentive, gender, race, age group Census region, Health state, 

MEC season, Urban-rural 1.383 1.197 1.597

Incentive, Gender, race, age group, HH size, 

interview mode, diab (Y/N), general health, health 

insurance

1.421 1.252 1.611

Incentive, Gender, race, age group, HH size, 

interview mode, diab (Y/N), general health, health 

insurance

Census region, Health state, 

MEC season, Urban-rural 1.365 1.180 1.579

9/27/2023
30

Incentive $85 Incentive $125 Examined Rate RR variance

Examined Interviewe

d Examined Interviewed $85 $125 $85 $125

Overall All 1244 1706 5383 6768 73% 80% 8.7 2.7

Race

NHW/O 682 932 3820 4801 73% 80% 12.7 0.4

NHB 268 388 661 824 69% 80%

Hispanic 294 386 902 1143 76% 79%

Gender Male 558 775 2439 3042 72% 80% 1.4 0.7

Female 686 931 2944 3726 74% 79%

Age

16-19 95 127 459 562 75% 82% 22.5 2.8

20-39 270 411 1291 1664 66% 78%

40-59 320 436 1419 1778 73% 80%

60+ 559 732 2214 2764 76% 80%

HH size

1-2 709 956 3078 3879 74% 79% 4.0 0.7

3-4 368 512 1594 2009 72% 79%

5+ 167 238 711 880 70% 81%

Interpreter used Yes 17 21 94 111 81% 85% 33.1 13.7

No 1227 1685 5289 6657 73% 79%

Language used 

in interview

English 1109 1529 5026 6326 73% 79% 7.0 0.9

Spanish 135 177 357 442 76% 81%

9/27/2023
31

Incentive $85 Incentive $125 Examined Rate RR variance

Examined Interviewe

d Examined Interviewe

d $85 $125 $85 $125

Overall All 1244 1706 5383 6768 73% 80% 8.7 2.7

With Health 

insurance*

Yes 1079 1470 4967 6231 73% 80% 5.6 2.0

No 159 227 404 520 70% 78%

SP self-reported 

general health*

Excellent 169 240 770 1001 70% 77% 5.1 2.7

Very good 364 511 1768 2209 71% 80%

Good 428 579 1889 2342 74% 81%

Fair/Poor 283 376 954 1213 75% 79%

Interview Mode In Person 462 642 2959 3666 72% 81% 1.2 3.3

Phone 782 1064 2424 3102 73% 78%

Diagnosed 

diabetes*

Yes 193 253 681 819 76% 83% 8.0 8.4

No 1049 1451 4702 5948 72% 79%

*Don't know/Refusal are excluded

9/27/2023