Table 3 Recruitment homophily, design effects and coefficient of discoverability for key variables by study

Homophily

 Age (continuous/categorical)^a

0.84/1.28

1.68/1.25

1.43/1.36

1.16/1.29

2.15/1.10

1.68/1.26

2.05/1.48

 Heroin use^b

1.44

1.10

1.27

1.02

1.21

1.28

1.23

 Fentanyl use^b

1.03

1.11

1.25

1.07

1.26

1.01

1.04

 Methamphetamine use^b

1.21

1.14

1.01

1.02

1.04

1.02

1.04

 Preferred drug for getting high

1.55

1.35

1.51

1.13

1.25

1.38

1.42

 HCV antibody status

1.16

1.18

1.01

1.11

1.08

1.01

1.11

 Homelessness^c

1.03

1.04

1.05

1.18

1.09

1.08

1.12

Design Effects

 Heroin use^b

5.23

2.48

3.80

3.58

3.64

3.40

2.91

 Fentanyl use^b

4.97

2.06

3.59

2.79

2.68

1.52

2.08

 Methamphetamine use^b

2.06

1.92

3.04

2.80

2.93

1.97

2.05

 HCV positive antibody status

5.42

2.46

3.22

2.58

2.99

3.21

2.67

 Homelessness^c

4.26

2.57

4.13

2.50

2.86

2.91

2.60

Coefficient of discoverability

1.12

0.90

1.29

1.28

1.05

1.02

1.27