The remaining sections of this article describe the reliability and validity characteristics of the test items and scaling methods using a large sample of patients participating in the NFO – World Group's CAP. The NFO CAP consists of over 250,000 people suffering from one or more of over 60 chronic ailments and conditions. The panel is a representative sampling of one out of every 191 households in America, prescreened for more than 50 pieces of demographic information so as to represent the demographic characteristics of the population of the citizenry of the USA (for more information see: ).
Patients were recruited for this portion of the study that had the same illness conditions as represented within the focus groups and interviews (anxiety/depression, arthritis, asthma, cancer, cardiovascular disease, diabetes, infectious disease, migraine, and psoriasis). They were also required to be at least 18 years of age, able to read English, and able to complete a questionnaire on-line. The broad sampling provided a range of treatment intents (i.e., curative, preventive and symptom management) as well as routes of medication administration (i.e., injection, oral, topical, inhalation).
Invitations were sent electronically to 10,000 NFO panel members across the United States. Participants that accessed the study site via the Internet were assessed for eligibility, equally stratified by illness condition and gender, and then randomly assigned into 1 of the 2 scale conditions (VAS or Likert-type scaling methods). Since many participants had multiple illness conditions, and were on several medications at the same time, respondents were helped to clearly identify which particular medication and illness condition were the subject of study. A total of 6,713 individuals responded (a response rate of 67.2%), from this pool individuals were sequentially offered the opportunity to participate based on the availability of participant slots in each stratum. Five hundred and eighty seven individuals passed screening and were enrolled, of these, 567 provided complete data sets, with 287 respondents in the VAS arm and 280 in the Likert-type arm.
In addition to completing the test items, respondents were asked to provide information about the length of time they had been on their medication, the method of its administration, the frequency and severity of any side effects they might have experienced, and the likelihood that they would continue to take the medication given its current level of effectiveness and side effects. They were also asked about perceptions of their current state of health, the severity of their illness, and some basic socio-demographic information (e.g., age, gender, educational level, and ethnic background).
Patients were recruited for this portion of the study that had the same illness conditions as represented within the focus groups and interviews (anxiety/depression, arthritis, asthma, cancer, cardiovascular disease, diabetes, infectious disease, migraine, and psoriasis). They were also required to be at least 18 years of age, able to read English, and able to complete a questionnaire on-line. The broad sampling provided a range of treatment intents (i.e., curative, preventive and symptom management) as well as routes of medication administration (i.e., injection, oral, topical, inhalation).
Invitations were sent electronically to 10,000 NFO panel members across the United States. Participants that accessed the study site via the Internet were assessed for eligibility, equally stratified by illness condition and gender, and then randomly assigned into 1 of the 2 scale conditions (VAS or Likert-type scaling methods). Since many participants had multiple illness conditions, and were on several medications at the same time, respondents were helped to clearly identify which particular medication and illness condition were the subject of study. A total of 6,713 individuals responded (a response rate of 67.2%), from this pool individuals were sequentially offered the opportunity to participate based on the availability of participant slots in each stratum. Five hundred and eighty seven individuals passed screening and were enrolled, of these, 567 provided complete data sets, with 287 respondents in the VAS arm and 280 in the Likert-type arm.
In addition to completing the test items, respondents were asked to provide information about the length of time they had been on their medication, the method of its administration, the frequency and severity of any side effects they might have experienced, and the likelihood that they would continue to take the medication given its current level of effectiveness and side effects. They were also asked about perceptions of their current state of health, the severity of their illness, and some basic socio-demographic information (e.g., age, gender, educational level, and ethnic background).