72 answered at least one question in the questionnaire with yes (please see Figure 2).
Both respondents to the questionnaire answered yes to the question on whether the causal diagram was easy to understand and useful to policy makers.
To be eligible for the parent study, patients had to be at least 40 years old and respond, on an initial phone questionnaire, "yes" when asked if they had knee pain for most of the last month that was relieved by rest, at least partially.
An analysis of those patients who gave opposing answers did not show any systematic error patterns, such as giving the same answers (e.g. only "yes") throughout the questionnaire or confusing "yes" and "no" (data not shown).
The following health-risk behaviours were measured at baseline using the questionnaire: regular smoking (yes vs. no), binge drinking (excessive drinking leading intoxication twice or more per month vs. less than twice per month) [ 27], and physical activity.
The questionnaire included five yes-no questions regarding regular intake of anti-cholesterol drugs, anti-hypertensive drugs, anti-diabetic drugs and corticosteroids, and history of gastrectomy.
- presence of a chronic disease (yes, no): The questionnaire asks about the presence of 18 different chronic diseases (e.g. hypertension, myocardial infarction, asthma).
The reception staff was instructed to consecutively ask the patients who contacted them when they prior or after the GP consultation whether they would be interested in taking part in the survey and gave the questionnaire to those who said yes.
The questionnaire goes far beyond a simple yes or no, gays in or gays out.
The questionnaire was structured with categorized questions (yes or no) and variables of interest, including questions about self-perception, appearance satisfaction, and orthodontic treatment need.
The responses to the items in the questionnaire mainly had the form of yes (agree), no (disagree), uncertain or refusal.
