This is perhaps not surprising given the diversity of populations studied and methodological concerns, including small numbers in five prospective studies, varying numbers of questions on consumption of fruits and vegetables (between 2 and 44 items), and the possibility of recall bias and other biases in case control studies.
The DHQ included questions on consumption of six types of alcoholic beverages: beer, Japanese sake (rice wine), shochu (a distilled alcoholic beverage made in Japan), chuhai (made with shochu and carbonated water), whisky, and wine.
The questionnaire also contains three photographs of scaled portions of four foods, questions on the overall frequency of fruit and vegetable consumption and questions on consumption of foods that do not fit easily into the frequency format, such as breads.
The FFQ also contains three photographs of scaled portions for four foods (used to calculate a portion size calibrator), questions on the overall frequency of fruit and vegetable consumption, and questions on consumption of foods that do not fit easily into the frequency format (such as breads).
Similarly, women in NHS II answered questions on consumption of alcohol in the 1989 and 1991 questionnaires.
The cohort included 11 980 pregnant women (87% of all invited), who at a routine visit to the midwife around the 36th gestational week, completed a questionnaire concerning lifestyle, demographic and health-related characteristics before and during pregnancy, including questions on consumption of alcoholic beverages during pregnancy.
Framing of questions of alcohol consumption with the use of prolonged or typical reference periods do not seem to eliminate seasonal variations in reporting of alcohol consumption.
Those who chose the options ' About 3 times a day or more, about twice a day, about once a day', when asked the question on consumption of sugary snacks between meals, were classified as not having undertaken preventive dental care.
The subjects were instructed to exclude tomatoes and cucumbers when they answered the question on consumption of vegetables, since these are traditionally served at each meal and has been affordable to all SES groups in Gaza at dumping prices.
For each species consumed, the participant was asked to answer questions about frequency of consumption and serving sizes.
