An assessment of the relative validity of retrospective interviewing for measuring dietary intake.

The relative validity of a method for determining dietary intake four years previously was assessed. In May 1981, 79 people (46 women and 33 men, aged 29-69 years) were interviewed by use of the dietary history method concerning dietary intake in 1977. These results were compared with those obtained in this same group by means of a seven-day record in February 1977. For daily intake of energy and selected nutrients, the differences in mean intake were generally below 10%, while for six examined food groups, larger differences in the median estimates were noted. The results provide evidence that retrospectively collected dietary data have some meaningfulness, although questions remain concerning whether the retrospective dietary history method is sufficiently valid for use in a particular epidemiologic study.