Risk of bias | High | Low | |
---|---|---|---|
General bias based on Bilotta et al. [32] | Selection bias (Inadequate randomisation) | No randomisation (site/tree selection based on availability, expert judgement or results) | Randomisation (site/tree selection based on random number generator/tossing a coin) |
Performance and detection bias (researcher bias) | No blinding/blinding broken/insufficient information | Blinding done | |
Reporting bias (incomplete results (variables)) | Not all pre-specified outcomes reported; measurements/methods for some outcomes were not pre-specified; incomplete reporting of one or more outcomes; not reporting on an expected outcome | Study protocol is available and pre-specified outcomes are reported on; study protocol not available but all expected outcomes are reported on | |
Attrition bias (incomplete results (observations)) | Resulting data points lower than expected from the methodology; no reason given for missing data related to outcome; bad imputation | Reported data points correspond to methodology; data omission or imputation well documented and justified | |
Adapted criteria | Number of spatial or temporal replications (experimental unit) and observations [33] | Spatial replication (experimental units) | |
2 fields (widespread application) | > 2 fields | ||
Or 2 rows (row-based installation) | > 2 rows | ||
Or 2 trees (targeted application) | > 2 trees | ||
OR | |||
Temporal replication | |||
1 frost night (temporal replication temperature change) | > 1 frost night | ||
1 year (temporal replication yield/damage) | > 1 year | ||
Observations (assessment level) per experimental unit | |||
< 4 trees (widespread or row-based) | ≥ 4 trees | ||
< 4 branches (targeted application) | ≥ 4 branches | ||
Baseline of test and control groups compared | At least one of the following differs or is not described: management (pruning), soil type, topographic position, differences in cultivar and/or rootstock, orchard age | All of the following factors are comparable: management (pruning), soil type, topographic position, differences in cultivar and/or rootstock, orchard age | |
Location of temperature sensor given | Closest meteorological station > 10 km away; no detail given | Local sensors on field and beside flowers at several tree heights (lower, middle and upper position in tree) | |
Reporting method | Mean effects per experiment only | Raw data, measure of variation | |
External validity | Cold chamber experiment | Field experiment |