Table 3.

Error Correlations Within^a and Between^b Self-Report Instruments for Total Carotenoid Intake in a WHEL Sample of 3,088 Breast Cancer Survivors Recruited Between 1995 and 2000 and Followed Through 2006

Assessment Methodc and Year	Error Correlation in Repeated Plasma Measures (r)
	r = 0				r = 0.3d
	Comparison (n = 1,551)		Intervention (n = 1,537)		Comparison (n = 1,551)		Intervention (n = 1,537)
	Error Correlation Estimate	95% Credible Interval	Error Correlation Estimate	95% Credible Interval	Error Correlation Estimate	95% Credible Interval	Error Correlation Estimate	95% Credible Interval
Within 24-hour recalls
Baseline, 1 year	0.32	0.27, 0.37	0.02	−0.06, 0.10	0.32	0.27, 0.38	0.00	−0.07, 0.08
Baseline, 4 years	0.27	0.21, 0.33	0.09	0.02, 0.16	0.27	0.21, 0.33	0.08	0.01, 0.15
1 year, 4 years	0.42	0.37, 0.48	0.59	0.53, 0.63	0.43	0.37, 0.48	0.59	0.54, 0.64
Within Arizona food frequency questionnaire
Baseline, 1 year	0.55	0.50, 0.59	0.19	0.12, 0.26	0.55	0.51, 0.59	0.17	0.10, 0.24
Baseline, 4 years	0.39	0.33, 0.44	0.23	0.17, 0.30	0.39	0.34, 0.44	0.23	0.16, 0.29
1 year, 4 years	0.51	0.46, 0.56	0.58	0.52, 0.63	0.51	0.46, 0.56	0.58	0.53, 0.63
Between Arizona food frequency questionnaire and 24-hour recalls
Baseline	0.40	0.36, 0.45	0.40	0.36, 0.45	0.41	0.36, 0.45	0.41	0.36, 0.45
1 year	0.42	0.36, 0.47	0.68	0.65, 0.72	0.42	0.36, 0.47	0.69	0.65, 0.72
4 years	0.39	0.34, 0.44	0.51	0.45, 0.56	0.39	0.34, 0.44	0.51	0.46, 0.56

Abbreviation: WHEL, Women's Healthy Eating and Living.

^aWithin-instrument error correlations represent systematic error and can be interpreted as the proportion of error variance due to subject-specific bias.

^bBetween-instrument error correlations represent shared systematic error (e.g., recall bias) between instruments.

^cSelf-reported dietary intakes adjusted for body mass index and total caloric intake; plasma markers adjusted for plasma cholesterol and body mass index.

^dAssumed first-order autoregressive correlation structure for plasma error matrix.