Table 2 Bias assessment framework of included articles
Bias area | Characteristic | Bias assessment | Bias score |
|---|---|---|---|
Selection and performance bias: study design | Sampling | Description of sampling method and transfer of samples to the laboratory | 10 |
Description of the sampling method or transfer of samples to the laboratory | 5 | ||
Method of sampling and transfer of samples to the laboratory is not described | 0 | ||
Sample size | Number of samples > 5 or sample size > 10 L | 10 | |
Number of samples < 5 or sample size < 10 L | 5 | ||
Lack of sample size and number of samples | 0 | ||
Replicates | Replication of samples | Yes [10] | |
No [0] | |||
Study timeframe | Sampling time of more than two seasons (cold and hot seasons, winter and spring or summer) | 10 | |
Sampling time of less than two seasons (hot or cold seasons) | 5 | ||
Sampling time is not described | 0 | ||
Assessment bias: measurement of outcome | Detection of ARGs | The laboratory method and DNA extraction are clear [such as PCR, qPCR, HT-qPCR, high-throughput sequencing (HTS)] Metagenomics | 10 |
Laboratory methods and DNA extraction are unclear or not described | 0 | ||
Chlorine measurement | Using standard methods to measure chlorine (exposure) | 10 | |
Using non-standard or unknown methods to measure chlorine (exposure) | 0 | ||
Confounders | Measuring confounding factors and their effects are applied (such as pH, temperature, DO, TOC, phosphate, and nitrate) | 10 | |
Measuring confounding factors, but their effects are not applied | 5 | ||
Unmeasured confounders | 0 | ||
Bias linked to clarity and publication bias | Statistical analyses | Using and describing the statistical data analysis method | Yes [10] |
No [0] | |||
Reporting bias | All the statistical tests, measurements, and variables mentioned in methods are reported in the results or additional files | Yes [10] | |
No [0] | |||
Other biases | Detection bias | Having significant differences in the results before and after chlorination | Yes [10] |
No [0] | |||
Attrition bias | Measuring the concentration or frequency of ARGs before and after chlorination | Yes [10] | |
No [0] | |||
Research aim consistency | Objectives of the study are clearly stated and the answer is consistent with the objectives | Yes [10] | |
No [0] |