In an experimental study, researchers are testing a new flea preventive medication on dogs using a blind study. Dogs are treated with the new medication or with a placebo. Who should know which dogs are given the medication or the placebo for this blind study?

If only the researchers know who received the treatment, it could still introduce bias, as their expectations or attitudes might inadvertently affect their interactions with the dogs or interpretation of the data. True blind studies require that all parties involved remain unaware of the treatment allocations to avoid any potential influence on the study's outcomes.

If all parties are informed, it eliminates the purpose of a blind study. Knowledge of who received the treatment could lead to conscious or unconscious biases, affecting how the medication is perceived and how responses are reported. This scenario compromises the validity and reliability of the study results.

Allowing dog owners to know which dogs received the medication could lead to biased expectations about the treatment's effectiveness. Owners might unconsciously influence their dogs' behavior or reporting based on their knowledge of the treatment, undermining the study's objectivity.