Table 2 Explanatory variables

INTRAVENOUS

=1 if a drug is administered intravenously (1, 0, 0, −1)

SUBCUTANEOUS

=1 if a drug is administered subcutaneously (0, 1, 0, −1)

INTRAMUSCULAR

=1 if a drug is administered ntramuscularly (0, 0, 1, −1). The reference category (−1) is administration via needle-free routes

DOSFREQ

Continuous variable referring to the number of unit administrations over a one year period for a single full course of treatment

NONCLINICAL_SELF

=1 if a drug is self-administered in non-clinical settings (1, 0, −1)

NONCLINICAL_SUPV

=1 if a drug is administered in non-clinical settings under the supervision of a qualified healthcare professional (0, 1, −1). The reference category (−1) is drug administration in clinical settings

DDA_MODERATE1

=1 if a given mode of administration is associated with moderate but manageable disruption to respondents’ daily activities (1, 0, 0, −1)

DDA_MODERATE2

=1 if a given mode of drug administration is associated with moderate disruptions to daily activities that a respondent cannot cope with (0, 1, 0, −1)

DDA_SEVERE

=1 if a given mode of drug administration is associated with severe disruption to the respondent’s daily activities (0, 0, 1, −1). The reference category (−1) is a mode of administration that carries no risk of disruption to patients’ daily activities

RAE_MODERATE

=1 if the risk of adverse events associated with a given mode of drug administration s moderate (1, 0, −1)

RAE_SEVERE

=1 if the risk of adverse events associated with a given mode of drug administration is severe (0, 1, −1). The reference category (−1) is drug delivery that is associated with no risk of adverse events

COST

Continuous variable indicating the time and travel costs borne by patients per unit administration

A

Alternative-specific constant = 1 for drug option A (1, −1). The reference point, drug option B = −1

FEMALE

=1 if survey respondent is female (1, −1). The reference category (−1) are males

RESPONDENTAGE

Continuous variable indicating the age of a survey respondent

VOCATIONAL

=1 if the highest level of education attained by a respondent is vocational training (1, 0, −1)

GCSEs_O + A

=1 if the highest level of education attained by a respondent is GCSEs O′ and A’ levels (0, 1, −1). The reference category (−1) are respondents with “higher education”

EMPLOYED

=1 if respondent is employed (1, −1). The reference category (−1) are those who are currently unemployed

INCOME_1

=1 if respondent’s annual household income is under £15,000 (1, 0, 0, 0, −1)

INCOME_2

=1 if respondent’s annual household income is between £15,000 and £29,999 (0, 1, 0, 0, −1)

INCOME_3

=1 if respondent’s annual household income is between £30,000 and £49,999 (0, 0, 1, 0, −1)

INCOME_4

=1 if respondent’s annual household income is between £50,000 and £75,000 (0, 0, 0, 1, −1). The reference category (−1) are respondents with annual household income in excess of £75,000

PRIOR_ ILLNESS

=1 if a survey respondent had received medical treatment under the advice or guidance of a qualified health worker over the past year (1, −1). The reference category (−1) are those who remained healthy over the past year