Table 3 Definition of response rates and primary and secondary outcomes

Number of emails with questionnaires on HA issues sent (N1)

The total number of emails with questionnaires on HA issues sent.

Number of emails with questionnaires on HA issues not bounced (N2)

The total number of emails with questionnaires on HA issues sent that had surveyees with valid email addresses.

Number of questionnaires for which the surveyee was available (N3)

The total number of emails with questionnaires sent to assess HA issues with surveyees with valid email addresses and for which the surveyee was available. Unavailability can be the result of, e.g., automated responses such as ‘out of office’, ‘study leave’, ‘on strike’, ‘vacation leave’, ‘maternity leave’

Number of partly or completely answered questionnaires (N4)

The total number of questionnaires on HA issues received back in which the questions were answered (either partial or completely).

Number of completely answered questionnaires (N5)

The total number of questionnaires on HA issues received back in which all questions were answered.

Overall response rates in questionnaires on HA issues

N4 or N5/N1, N2, or N3

Number of questionnaires that answered the question on review item 1^a (N6)

The total number of questionnaires received back in which the question on review item 1^a was answered.

Response rate on review item 1^a

N6/N1, N2, N3, N4 or N5

Number of questionnaires in which the respondents reported review item 1^a (N7)

The number of questionnaires in which the respondents reported review item 1^a, i.e., perceiving other co-author(s) as honorary author(s) on a publication.

Prevalence of review item 1^a (primary outcome)

N7/N6

Number of questionnaires that answered the question on review item 2^b (N8)

The total number of questionnaires received back in which the question on review item 2^b was answered.

Response rate on review item 2^b

N8/N1, N2, N3, N4, or N5.

Number of questionnaires in which the respondents reported review item 2^b (N9)

The number of questionnaires in which the respondents reported review item 2^b, i.e., having been approached by others to include honorary author(s) on a publication.

Prevalence of review item 2^b (primary outcome)

N9/N8

Number of questionnaires that answered the question on review item 3^c (N10)

The total number of questionnaires received back in which the question on review item 3^c was answered.

Response rate on review item 3^c

N10/N1, N2, N3, N4, or N5

Number of questionnaires in which the respondents reported review item 3^c (11)

The number of questionnaires in which the respondents reported review item 3^c, i.e., admitting being an honorary author on a publication.

Prevalence of review item 3^c (secondary outcome)

N11/N10

Number of questionnaires that answered the question on review item 4^d (N12)

The total number of questionnaires received back in which the question on review item 4^d was answered.

Response rate on review item 4^d

N12/N1, N2, N3, N4, or N5.

Number of questionnaires in which the respondents reported review item 4^d (N13)

The number of questionnaires in which the respondents reported review item 4^d, i.e., admitting adding an honorary author(s) on a publication.

Prevalence of review item 4^d (secondary outcome)

N13/N12

Number of questionnaires that answered the question on review item 5^e (N14)

The total number of questionnaires received back in which the question on review item 5^e was answered.

Response rate on review item 5^e

N14/N1, N2, N3, N4 or N5

Number of questionnaires in which the respondents reported review item 5^e (15)

The number of questionnaires in which the respondents reported review item 5^e, i.e., admitting having approached others to include honorary author(s) on a publication.

Prevalence of review item 5^e (secondary outcome)

N15/N14