# Table 1 Descriptive statistics of respondents and non-respondents

Response status   Weighted balancea
Did not respond Responded Total Meanb Ratioc
N (%) 8264 (94.8) 451 (5.2) 8715 (100.0)
Medical training
MD 7663 (92.7) 417 (92.5) 8080 (92.7)
DO 601 (7.3) 34 (7.5) 635 (7.3) 0.000 1.002
Sex
Male 5523 (66.8) 259 (57.4) 5782 (66.3)
Female 2741 (33.2) 192 (42.6) 2933 (33.7) 0.000 1.002
Physician specialty
Critical care medicine 826 (10.0) 54 (12.0) 880 (10.1)
Emergency medicine 1586 (19.2) 92 (20.4) 1678 (19.3) 0.000 1.002
Family medicine 1688 (20.4) 79 (17.6) 1767 (20.3) 0.000 1.002
Hospitalist 835 (10.1) 54 (12.0) 889 (10.2) 0.000 1.002
Infectious disease 814 (9.8) 56 (12.4) 870 (10.0) 0.000 1.002
Internal medicine 1684 (20.4) 68 (15.1) 1752 (20.1) 0.000 1.002
Pulmonary critical care 831 (10.1) 47 (10.4) 878 (10.1) 0.000 1.002
Years since residencyd 17.8 (11.1) 17.5 (10.8) 17.8 (11.1) 0.000 1.002
Type of practice
Office 5997 (72.6) 315 (70.0) 6312 (72.4)
Hospital staff 2134 (25.8) 128 (28.4) 2262 (26.0) 0.000 1.002
Teaching 133 (1.6) 7 (1.6) 140 (1.6) 0.000 1.002
1. a Weighted balance is based on diagnostic output produced by the kmatch module
2. b Mean is the standard difference in means between weighted respondents and weighted non-respondents; standard difference is 0 when perfectly balanced. Standard difference in means is rounded to 3 significant digits
3. c Ratio represents the ratio of variances of weighted non-respondents to variance of weighted respondents; ratio is 1 when perfectly balanced. Ratio of variances is rounded to 3 significant digits
4. d Reports mean Years since residency with standard deviation in parentheses