| 查看: 766 | 回复: 3 | ||
| 本帖产生 1 个 翻译EPI ，点击这里进行查看 | ||
听涛月雨金虫 (小有名气)
|
[求助]
一小段数据统计分析的描述，欢迎应助
|
|
|
A geometric mean provides a better estimate of central tendency for data that are distributed with a long tail at the upper end of the distribution. This type of distribution is common in the measurement of environmental chemicals in blood or urine. The geometric mean is influenced less by high values than is the arithmetic mean. Geometric means were calculated by taking the log of each concentration and then computing the weighted mean of those log-transformed values using SUDAAN software. Ninety-five percent confidence intervals around this weighted mean were calculated by adding and subtracting an amount equal to the product of a Student’s t-statistic and the standard error of the weighted mean estimate. The degrees of freedom of the t-statistic were determined by subtracting the number of strata from the number of primary sampling units (PSUs) according to the data available from the complex survey design. The standard error was computed with SUDAAN’s Proc Descript (design=WR), which uses Taylor series linearization for variance estimation. The weighted geometric mean and its confidence limits were then obtained by taking the antilogs of this weighted mean and its upper and lower confidence limits. [ 来自科研家族 快乐检索 ] [ Last edited by 听涛月雨 on 2012-11-12 at 11:11 ] |
回复此楼» 猜你喜欢
0703 物理化学调剂
已经有5人回复
-
化学工程321分求调剂
已经有7人回复
-
0703化学调剂 290分有科研经历，论文在投
已经有7人回复
-
308求调剂
已经有3人回复
-
本人考085602 化学工程 专硕
已经有10人回复
-
焦虑
已经有9人回复
-
0856求调剂
已经有3人回复
-
283求调剂
已经有11人回复
-
深圳大学硕士招生（2026秋，传感器方向，仅录取第一志愿）
已经有8人回复
-
0703化学调剂
已经有7人回复
fanliang1389
荣誉版主 (文坛精英)
有爱的二哥
- 翻译EPI: 57
- 应助: 18 (小学生)
- 贵宾: 1.989
- 金币: 13044.6
- 散金: 18540
- 红花: 123
- 沙发: 243
- 帖子: 18237
- 在线: 2429.4小时
- 虫号: 620773
- 注册: 2008-10-09
- 性别: GG
- 专业: 食品加工学基础
- 管辖: 博后之家
【答案】应助回帖
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
听涛月雨: 金币+10, 翻译EPI+1, ★有帮助, 有帮助，谢谢！但翻译的不是很好，很多统计术语没有翻译出来 2012-11-12 14:25:31
sltmac: 金币+20 2012-11-13 11:00:03
听涛月雨: 金币+10, 翻译EPI+1, ★有帮助, 有帮助，谢谢！但翻译的不是很好，很多统计术语没有翻译出来 2012-11-12 14:25:31
sltmac: 金币+20 2012-11-13 11:00:03
| 对于在顶端处有长间隔分布的数据，几何平均值可较好的估计该类数据的集中趋势。通常，这类分布用来测量血液和尿液中的环境化学物。与算术平均值相比，几何平均数更不易受大数值的影响。几何平均数计算方法如下：取各浓度的log值，然后采用SUDAAN软件计算经log转化后数值的加权平均数。通过加减学生t检验结果和加权平均数标准误差的平均数来计算加权平均数的95%置信区间。依据复杂取样设计中所取有效数据，初级抽样单位（PSUs）减去层数即为t-检验的自由度。采用SUDDAN Pro Descript(design=WR)计算标准误差，其原理为泰勒级数线性方差估计。加权平均数的反对数值即为加权几何平均数，加权平均数的上部和下部界限即为其置信界限。 |
2楼2012-11-12 13:45:54
3楼2012-11-12 23:00:08
 |
4楼2012-11-13 08:37:54
