Briefly describe the significance of "three R" (RR, AR and OR) indicators in epidemiological investigation.

RR, also known as risk ratio or ratio ratio, is the most useful index to reflect the intensity of correlation between exposure and morbidity (death).

. RR showed that the risk of illness or death in exposed group was several times higher than that in unexposed group. The larger the RR value, the greater the influence of exposure and the greater the exposure intensity related to the result. That is, the ratio of morbidity or mortality between contact group and non-contact group.

2. Attributable risk

Also known as specific risk, rate difference (RD) and excess risk,

It is the absolute value of the difference between the incidence of exposure group and the incidence of control group, indicating the degree to which the risk is specifically attributed to exposure factors.

3. odds ratio, OR): also known as odds ratio, odds ratio and cross product ratio, it refers to the ratio of the exposed and unexposed in the case group divided by the ratio of the exposed and unexposed in the control group. This is an index reflecting the strength of the connection between disease and exposure.