笔记_Prognosis_week 1

一. prognosis的作用和在医学领域的应用案例

intercept:

interaction term
Without interaction terms, the effect of the two variables, blood pressure and age is independent. Whether you are young or whether you are old, blood pressure is affecting risk the same. As blood pressure goes up, risk is going up. But with the interaction term, blood pressure is having less of an effect on risk when the patient is old than when they are young.

二. 评估prognosis模型

1. when the patient with the worst outcome has the higher risk score (lower), this pair is called concordant (discordant).
2. we have different outcomes, but a tie in the risk score. In this case, we don’t consider it concordant or discordant. We classify these as ties
3. we don’t consider pairs where the outcomes are same.
4. A pair where the outcomes are different is called a permissible
   pair.
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   C_Index is used to evaluate the performance of the model.
   1) formula
   
   2) interpretation
   
   3) example