数字差异和概率差异对比率偏差的影响

比率偏差是一种常见的决策偏差,指的是当小概率事件以不同比率形式呈现时,人们倾向于认为以较小数字呈现的事件更不可能发生.本文采用问卷调查方式,在两个研究中分别探讨了数字差异和概率差异对比率偏差的影响,结果发现：（1）比率偏差的产生具有跨情境的一致性和稳健性;（2）等概率条件下比率偏差的发生率不随两个比率间的数字差异的增大而增大;（3）不等概率条件下比率偏差程度不随两个比率间概率差异的改变而改变.

The Influence of Numerical Difference and Probabilistic Difference on the Ratio Bias

The ratio bias is the tendency for people to judge a low probability event as more likely when presented as a large-numbered ratio ,such as 10/100, than as a smaller-numbered but equivalent ratio, such as 1/ 10. The purpose of the present study is to explore the influence of numerical difference and probabilistic difference on the ratio bias. Questionnaire was em ployed, and hypothetical scenarios were hunting job and seeing doctor. The results are demonstrated as follows：（ 1 ） The ratio bias could show cross-situational consistency; （2） In the condition of equal probability（ Study 1 ）, the ratio bias was statistically significant, however, different expressions of equal-probability made no significant difference on the ratio bias. （3） In the condition of unequalprobability （Study 2） ,both the ratio bias and independent variable levels didn＇t acquire significance, indicating that individuals do not always prefer to the large number than the small ones. Results suggest that people may not always prefer to large-numbered ratio ,and the ratio bias has no stable possibility premise.