Measurement error inherent in diet and physical activity assessment tools hinders research to assess the associations between diet, physical activity, and health outcomes. Given the high penetrance of internet and mobile devices in the population and the availability of motion-sensing devices for monitoring physical activity, web-enabled instruments that can be accessed remotely and repeatedly administered are increasingly a practical and economical approach for measuring diet and physical activity exposures in health studies.

To understand the measurement error properties of both new and conventional diet and physical activity assessment tools, the Interactive Diet and Activity Tracking in AARP (IDATA) was conducted. The purpose of the IDATA study was to evaluate and compare the measurement error structure of diet and physical activity assessment tools against reference biomarkers.

IDATA Study participants were recruited from a list of AARP members aged 50-74 years residing in and around Pittsburgh, Pennsylvania. Eligible and consented participants visited the study center three times and also completed assigned activities at home over a 12-month period.

The following diagram illustrates how the cohort was defined starting with all of the participants recruited.

Participants were assigned to Groups 1, 2, 3, or 4 and followed a specified 12-month assessment protocol. Groups 1 and 3 followed the same assessment schedule whereby reference biomarkers were collected during the first month of assessment. Groups 2 and 4 followed an alternative assessment schedule whereby reference biomarkers were collected during the sixth month of assessment. A subsample of participants (designated by S below; n= 66) were recruited to provide repeated measures of reference biomarkers.

Months for Groups 1 & 3

	M0	M1	M2	M3	M4	M5	M6	M7	M8	M9	M10	M11
Clinic Visit	X						X					X
Physical Activity
ACTIGRAPH	X						X
ACTIVPAL	X						X
ACT24	X		X		X		X		X		X
Fitness Test	X
PAQ-CHAMPS	X						X
PAQ-AARP				X						X
PAQ-BRFSS				X						X
PAQ-Harvard												X
PAQ-Stanford	X						X
HRM	X
Dietary
ASA24		X		X		X		X		X		X
DHQ-II	X											X
Daily Food List	X											X
4-Day Food Record			X						X
Biomarkers
DLW	X						S
Urine	X						X
Saliva	X						X
Status
Anthropometry	X						X					X

S = subsample only

Months for Groups 2 & 4

	M0	M1	M2	M3	M4	M5	M6	M7	M8	M9	M10	M11
Clinic Visit	X						X					X
Physical Activity
ACTIGRAPH							X					X
ACTIVPAL							X					X
ACT24		X		X			X		X		X	X
Fitness Test							X
PAQ-CHAMPS	X						X
PAQ-AARP				X							X
PAQ-BRFSS				X							X
PAQ-Harvard												X
PAQ-Stanford							X					X
HRM						X
Dietary
ASA24	X		X		X			X		X		X
DHQ-II	X											X
Daily Food List	X											X
4-Day Food Record			X							X
Biomarkers
DLW							X					S
Urine							X					X
Saliva						X						X
Status
Anthropometry	X						X					X

S = subsample only