Common source bias is when people form judgments or make decisions based on their personal experiences or beliefs. It's like when you think apple juice is better than orange juice because you've always liked it, even if someone might think orange juice is better or healthier.
In science or research, common source bias can happen when researchers bias their study or interpretation of results because of their own beliefs or prejudices. For example, if a researcher believes that people who exercise are healthier, they may unconsciously choose or interpret data that supports this belief, even if other data shows other factors that might contribute to health.
Common source bias can be a problem because it can lead to inaccurate or unfair conclusions, and if people rely on these conclusions, it can lead to misunderstandings and harmful outcomes. That's why it's important for researchers and anyone making decisions to be aware of their own biases and try to look at things objectively, like considering all the different factors that could influence a situation or result.