Sometimes an advert or a political message may deliberately (or intentionally) put some sort of spin on data and mislead those seeing it. As researchers and professionals, we would all, I hope, try to avoid this deliberate bias, but we may still have unintentional bias due to the choice of sample or other aspects of our study methods. For example, if you interview people in an Apple store and ask them for their favourite phone model, the result may be somewhat skewed! Of course, unintentional bias is not always so obvious; for example, if you interview members of a particular social media network, it may include more younger people, or more well-off people, and this might have an impact on music taste or even favourite food.
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