Table 3 Survey research design
| Â | Survey 1: All primary care and pain specialist physicians in intervention states | Survey 2: Primary care and pain specialist physicians registered to recommend cannabis to patients | Survey 3: People with chronic non-cancer pain |
|---|---|---|---|
Survey administration | |||
33. Questionnaire administration | Mixed-mode email/postal survey | Online survey fielded by AmeriSpeak. Panel members can choose either web or telephone survey administration. | |
34. Dates of data collection | Anticipated January–June 2022 | Anticipated May–June 2022 | |
35. Number and types of contact | Up to 8 contacts: introductory letter delivered by email and post; email survey waves 1–3; postal survey waves 1–2; reminder postcard; postal survey wave 3. Once a physician responds to the survey, they will not receive further contact. | Up to 10 contacts; email or telephone follow-ups to non-responders depending on preferred mode of administration. | |
36. Data entry | Email survey responses will be captured directly in an electronic database. Postal survey responses will be double-entered into an electronic database by two research team members; discrepancies will be identified and reconciled. | Web survey responses will be captured directly in an electronic database. Telephone responses will be entered into an electronic database by AmeriSpeak staff. | |
Sample selection | |||
37. Sample frame | Primary care and pain specialist physicians in the National Provider Plan and Enumeration System (NPPES), a physician database maintained by the Centers for Medicare and Medicaid Services (CMS). | Primary care and pain specialist physicians registered to recommend medical cannabis in the 10 study states with medical cannabis laws that require physicians to register with the state in order to recommend cannabis to patients. | NORC’s AmeriSpeak Panel of ≈35,000 adults aged 18+. |
38. Sample size calculation | Sample sizes were determined based on a margin of error calculation showing that with the expected number of completed surveys (N ≈ 1000 for all three surveys), results would have a margin of error of 2–3 percentage points. | ||
39. Representativeness | The NPPES sample frame includes all US physicians who bill government and commercial insurers. | The sample frame includes all physicians registered in their state to recommend cannabis. | The AmeriSpeak panel is sourced from NORC’s area probability sample and from a US Postal Service address-based sample covering 97% of US households. |
40. Method of sample selection | Simple random sample | ||
41. Sample size | N = 2000 fielded surveys; expected response rate 50%, for N ≈ 1000 completed surveys. | N = 1500 fielded surveys; expected response rate 70%, for N ≈ 1000 | |
Survey instrument | |||
42. Instrument development | The research team will develop domains and preliminary items based on the research questions and on the results of aim 3 qualitative interviews. We will use items with established reliability and validity when available, and conduct cognitive interviewing with convenience samples of physicians and patients to support development of new items. | ||
43. Pre-testing | The study team will pre-test each survey with ≈25 physicians | NORC will pre-test the survey with ≈25 AmeriSpeak panelists. | |
44. Reliability and validity | In addition to using established items when available and conducting cognitive interviewing as noted above, we will conduct exploratory factor analysis to assess reliability of items within domains. | ||
45. Scoring methods | We will examine the distribution of responses to each survey item using descriptive statistics. | ||
Response rates | |||
46. Response rate calculation | Response rate will be calculated as the proportion of eligible physicians who complete the survey. | Completion rate will be calculated as the proportion of AmeriSpeak panelists selected for the survey who complete the survey. Response rate will be calculated to incorporate the panel recruitment rate as well as the completion rate per AAPOR guidelines for probability-based panel surveys. | |
47. Nonresponse | For all surveys, we will assess whether measured characteristics differ among respondents versus non-respondents. Survey weights will adjust for differential response. | ||
Reporting | |||
48. Alignment with objectives | Results reporting will align with study aims. | ||
49. Sub-group results | Sub-group analyses will align with study aims and sub-group Ns will be reported. | ||