The use of incentives in vulnerable populations for a telephone survey: a randomized controlled trial

BMC Research Notes

Table 1 Final dispositions for all households in each group

Final Disposition	Number of Households in Incentive Group (%) n=364	Number of Households in Non-Incentive Group (%) n=364	Between Group Difference (95% Confidence Interval)
Completed Interviews	100 (27.5%)	78 (21.4%)	6.0% (−0.2%, 12.3%)
Language Problem ¹	29 (8.0%)	26 (7.1%)	0.8% (−3.0%, 4.7%)
Partial Interview ²	5 (1.4%)	6 (1.6%)	−0.3% (−2.0%, 1.5%)
Problem With Number ³	38 (10.4%)	45 (12.4%)	−1.9% (−6.5%, 2.7%)
Non Contact ⁴	53 (14.6%)	59 (16.2%)	−1.6% (−6.9%, 3.6%)
Abbreviated Questionnaire ⁵	26 (7.1%)	27 (7.4%)	−0.3% (−4.0%, 3.5%)
Refusal	93 (25.5%)	102 (28.0%)	−2.5% (−8.9%, 4.0%)
Wrong Address ⁶	17 (4.7%)	18 (4.9%)	−0.3% (−3.4%, 2.8%)
No Qualified Sample ⁷	3 (0.8%)	3 (0.8%)	0.0 (−1.3, 1.3)

¹ Language problem refers to a respondent who was not fluent in French or English and could therefore not complete the survey.
² Partial interview refers to a respondent who, after beginning the interview, could not finish the entire survey. Partially interviewed subjects all needed to confirm that the given information could be used in research analysis.
³ Problem with number refers to numbers which were out of service, fax machine numbers or business telephone numbers.
⁴ Non-Contact refers to respondents who were never reached.
⁵ Abbreviated questionnaire refers to respondents who refused to complete the full interview but who agreed to answer a short series of condensed questions. The abbreviated questionnaire asked if anyone in the household had a food allergy and if the answer was yes, a short series of demographic questions were asked.
⁶ Wrong address refers to letters which were returned due to a wrong address; these households were therefore never contacted.
⁷ No qualified sample refers to households where no eligible participants resided.

ISSN: 1756-0500