No reliable control group

The study lacks a clearly defined and appropriately controlled comparison group, making it difficult to interpret the effects of the intervention.

Insufficient sample size

Poor outcome measures

The outcomes assessed are either poorly defined, not directly relevant, or not suitable indicators of training effectiveness or welfare.

Confounding variables not addressed

The analysis does not account for important variables that may influence the results (e.g., breed, prior training, handler skill).

Not peer-reviewed

The source is not peer-reviewed or does not meet basic standards of scientific rigor.