Figure 1From: Relative validity of the food frequency questionnaire used to assess dietary intake in the Leiden Longevity Study Bland-Altman plot of total energy intake. Differences in the daily intake of total energy estimated with 24-hour recalls and a food frequency questionnaire, plotted against the mean daily intake estimated by the two methods (N=128). Mean difference and 95% limits of agreement (1.96 × SD of mean difference) are included.Back to article page