Table 2 Checklist for the assessment of the methodological quality of the reviewed studies
Part 1 Sampling and representativeness | Points | |
1. Sampling method | ||
A | Non-probability sampling (including purposive, quota, convenience and snowball sampling) | 0 |
B | Probability sampling (including simple random, systematic, stratified, cluster, two-stage and multistage sampling) | 1 |
2. Was the response rate reported? | ||
A | Not reported | 0 |
B | Response rate below 50% | 0 |
C | Response rate at 50% or above | 1 |
3. Are the individuals selected to participate in the study likely to be representative of the target population? | ||
A | No | 0 |
B | Yes | 1 |
4. Selection bias: Is there a risk of selection bias caused by the inadequate selection of participants | ||
A | High risk | 0 |
B | Low risk | 1 |
5. Is the sample size adequate for establishing relationships (assumption of statistical power) | ||
A | No | 0 |
B | Yes | 1 |
Part 2 Measurement and confounders | ||
6. How was workplace bullying measured? | ||
A | Self-labeling without definition of the bullying concept | 0 |
B | Self-labeling with a definition of the bullying concept | 1 |
C | Behavioural checklist (e.g. NAQ, LIPT) | 1 |
7. How was bystanding assessed? | ||
A | Single-item question | 0 |
B | Behavioural checklist | 1 |
8. Performance bias: Is there a risk of performance bias caused by the inadequate measurement of exposure | ||
A | High risk | 0 |
B | Low risk | 1 |
9. Are the statistical methods appropriate for the study design? | ||
A | No/cannot tell | 0 |
B | Yes | 1 |
10. Were meaningful demographic covariates included? | ||
A | No | 0 |
B | Yes | 1 |
11. Were other work factors adjusted for? | ||
A | No | 0 |
B | Yes | 1 |
12. Is the study design cross-sectional or prospective (with time lag)? | ||
A | Cross-sectional | 0 |
B | Prospective | 1 |
13. Was previous the outcome variables adjusted for in prospective analyses? | ||
A | No | 0 |
B | Yes | 1 |
14. Confounder bias: Is there a risk of bias caused by the inadequate confirmation and consideration of confounding variable | ||
A | High risk | 0 |
B | Low risk | 1 |