Volume 16, Number 11—November 2010
Dispatch
Comparison of Survey Methods in Norovirus Outbreak Investigation, Oregon, USA, 2009
Table 1
Comparison of Internet- and telephone-based survey responses among participants of September 2009 bicycle ride, Oregon, USA*
Survey response | No. respondents/total no. participants (%)† |
Ratio (95% CI) | |
---|---|---|---|
Internet-based survey | Telephone survey | ||
Initiation of survey | 153/201 (76) | 76/91 (84) | 0.9 (0.8–1.02) |
Confirmed ride participation | 137/153 (90) | 72/76 (95) | 0.9 (0.9–1.02) |
Completed survey | 129/137 (94) | 72/72 (100) | 0.9 (0.9–0.98) |
Overall completion rate | 129/201 (64) | 72/91 (79) | 0.8 (0.9–0.98) |
Completed surveys within 2 days after survey release | 92/129 (71) | 47/72 (65) | 1.1 (0.9–1.3) |
Answered 90% of questions about food items | 74/129 (57) | 68/72 (94) | 0.6 (0.5–0.7) |
Attack rates‡ | 23/126 (18) | 13/72 (18) | 1.0 (0.5–1.9) |
*CI, confidence interval.
†Number of riders who answered the question compared with number of riders who were asked.
‡Three respondents to the Internet-based survey who reported illness that did not meet the case definition were excluded from analysis for attack rates.