Faulty logic

“No comparison needed!”

Unless an intervention is compared to something else, it is not possible to know what would happen without it.

Without a comparison, it is difficult to say that an intervention is the reason something happened.

If livestock get better or worse after a change or intervention, you are comparing how they were after the intervention to how they were before it. The problem with such “before and after” comparisons is that you don’t know what would have happened without the intervention.

For example, if you change the diet of a group of cattle with a respiratory disease, and the cattle improved, it might seem like the change of diet helped. However, they may have got better without the dietary change. The best way to find out if the diet made a difference would be to compare two groups of cattle with the respiratory disease, one with the changed diet and one without the change, and to make sure that it was a fair comparison.

BEWARE of intervention claims when you don’t know what the comparison was, and when they are based on before and after comparisons.

REMEMBER: Ask what the intervention was compared to, and whether it was a fair comparison.