🧪 相对风险（RR）计算器Relative Risk Calculator
根据 2×2 列联表（暴露组/对照组 × 发生/未发生）计算相对风险 RR 及 95% 置信区间、绝对风险差、需治疗人数 NNT 和比值比 OR。Calculate relative risk (risk ratio) with a 95% confidence interval from a 2×2 table — exposed/control × event/no event — plus the absolute risk difference, number needed to treat (NNT) and odds ratio.
使用说明与常见问题How-to & FAQ
「相对风险（RR）计算器」是什么？What is the Relative Risk Calculator tool?
根据 2×2 列联表（暴露组/对照组 × 发生/未发生）计算相对风险 RR 及 95% 置信区间、绝对风险差、需治疗人数 NNT 和比值比 OR。Calculate relative risk (risk ratio) with a 95% confidence interval from a 2×2 table — exposed/control × event/no event — plus the absolute risk difference, number needed to treat (NNT) and odds ratio.
如何使用「相对风险（RR）计算器」？How do I use the Relative Risk Calculator tool?
在「相对风险（RR）计算器」中，填写「暴露组：发生事件人数 a」、「暴露组：未发生 b」、「对照组：发生事件人数 c」、「对照组：未发生 d」、「置信水平」等参数，结果会随输入实时计算并显示在下方。In the Relative Risk Calculator: Fill in "Exposed group: events a", "Exposed group: no event b", "Control group: events c", "Control group: no event d", "Confidence level"; results are recalculated instantly as you type.
相对风险怎么算？How is relative risk calculated?
RR = [a ÷ (a + b)] ÷ [c ÷ (c + d)]，即暴露组发生率除以对照组发生率。RR = 1 表示无差异，大于 1 表示暴露增加风险。RR = [a ÷ (a + b)] ÷ [c ÷ (c + d)] — the event rate in the exposed group divided by the rate in the control group. RR = 1 means no difference; above 1 means higher risk with exposure.
置信区间用什么方法？Which confidence interval method?
采用 Katz 对数法：ln(RR) ± z × √(1/a − 1/(a+b) + 1/c − 1/(c+d))，再取指数。某格为 0 时该方法不适用。The Katz log method: ln(RR) ± z × √(1/a − 1/(a+b) + 1/c − 1/(c+d)), then exponentiated. It does not apply when a cell is 0.
RR 和 OR 有什么区别？How does RR differ from the odds ratio?
RR 比较的是概率，适用于队列研究和临床试验；OR 比较的是比值，常用于病例对照研究。事件罕见时两者接近。RR compares probabilities and suits cohort studies and trials; OR compares odds and is used in case-control studies. They are close when events are rare.
计算精度如何？How precise are the results?
「相对风险（RR）计算器」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Relative Risk Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「相对风险（RR）计算器」免费吗？需要注册吗？Is the Relative Risk Calculator free? Do I need an account?
「相对风险（RR）计算器」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Relative Risk Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.