Ascertainment bias involves making assumptions such as stigmas, stereotyping, ageism, and racism. Which is this bias called?

• A. Availability Bias
• B. Confirmation Bias
• C. Ascertainment Bias
• D. Hindsight Bias

Answer: (C)

Ascertainment bias occurs when data collection or observation is shaped by preconceptions, so what gets noticed, recorded, or emphasized is influenced by stigmas, stereotypes, ageism, or racism. This means certain observations are more likely to be sought or highlighted while others are overlooked, leading to biased conclusions that reflect those biases rather than the true situation. The description you provided fits this bias because the prejudice affects how information about people is gathered or interpreted, not merely what happens in memory or what seems obvious.

Other biases operate differently: availability bias is about what is most memorable or salient; confirmation bias is the tendency to look for information that supports what you already believe; hindsight bias is thinking events were predictable after they occur. So the issue described is ascertainment bias.