【推荐】计算四个表、R*C列表的小软件，非常好用
近来，很多战友在网上问我，有没有方便的比较率的软件。SPSS比较慢，对统计也要一定的基础和功底。下面介绍一个小软件。EPICALC 2000.很小，但是非常实用（2M不到）。
EpiCalc 2000 v1.02”是一个很好用的统计小软件，可以快速地输入数据，进行卡方检验、趋势检验、率的比较等等，直接将四格表或列联表数据输入即可，无须使用SPSS建立数据库，方便、省时
点击软件。安装（对系统要求很小）
然后右键点击“TABLE”，选择R*C，或者2*2（分层和不分层两种情况），数据输入。然后确定，OK，简单吧~~~快去试试吧！
当然还可以算趋势性卡方。这个很有趣。
大家也许会问，趋势性卡方有什么作用。
比如：住院时间和CR-BSI。我吧时间分为2天。5天。7天，10天（随便举例，实际要根据数据而定），然后看时间对发生CR-BSI是否增加了发病风险。这就趋势检验了。
尤其对于连续性变量而言。
但是请注意，这只是CRUDE OR。如果是要调整，比如LOGISTIC 回归，那么这个就不适用啦！
那么怎么才能调整呢，请思考？！（哈哈，卖个关子哦）
抢到沙发做了{:1_14:}。先下载，先学习！若有不会再请教鱼儿小弟！{:1_17:} 落花生 发表于 2012-1-19 00:11 static/image/common/back.gif
抢到沙发做了。先下载，先学习！若有不会再请教鱼儿小弟！
哪里。不胜荣幸！您可以试试看，可操作性非常强！ 有没有epicalc 2000 for Mac的？
exe文件，我的电脑不能使用的。 用它来算：Sample Size, Precision, and Power
19: Sample Size, Precision, and Power
A study that is insufficiently precise or lacks the power to reject a false null hypothesis is a waste of time and
money. A study that collects too much data is also wasteful. Therefore, before collecting data, it is essential to
determine the sample size requirements of a study. Before calculating the sample size requirements of a study you
must address some questions. For example:
• Do you want to learn about a mean? a mean difference? a proportion? a proportion (risk) ratio? an odds ratio? a
slope?
• Do you want to estimate something with a given precision or do you want to test something with a given
power?
• What type of sample(s) will you be working with? A single group? Two or more independent groups? Matched
pairs?
Let us first address the problem of estimating a mean or mean difference with given precision.
Sample Size Requirements for Estimating a Mean or Mean Difference
To determine an appropriate sample size you must first declare an acceptable margin of error d. Recall that margin of
error d is the wiggle room around the point estimate. This is equal to half the confidence interval width. When
estimating μ with 95% confidence use
Example: To obtain a margin of error of 5 for a variable with a standard deviation of 15, n = (4)(152)/(52) = 36.
This method is applied to estimating a mean difference based on paired samples (μd) by using the standard deviation
of the DELTA variable (sd) in your formula:
With independent samples, use the pooled estimate of standard deviation (sp) as your standard deviation estimate:
You should put considerable effort into getting a good estimate of the standard deviation of the variable you are
studying since sample size calculations depend on this fact. Such estimates come from prior studies, pilot studies,
and “Gestalt” (a combination of sources that contribute to knowledge about the variable).
EpiCalc 2000: Right click the tree window and select Sample > Precision > Single mean. Enter the
standard deviation estimate into the SD field and the required margin of error (d) into the Precision field. Because
Page 19.2 (C:\DATA\StatPrimer\sampsize.wpd © B. Gerstman 5/15/03)
EpiCalc 2000 uses a slightly different formula than those above, its sample size calculation will be slightly smaller.
This should not concern you because the problem with sample size calculations come not from small differences in
formulas but from differences in values entered into the formula. Sample size calculations are always rough.
Sample Size Requirements for Testing a Mean or Mean Difference
Power (1!b) is the probability of avoiding a type II error. A type II error occurs when you retain a false H0.
Conventional practice is to determine the sample size that gives 80% power at the 0.05 level of significance (twosided).
This can be determined with:
(Dallal, 1997, www.tufts.edu/~gdallal/SIZE.HTM) where
n represents the required sample size per group
D represents the expected mean difference (a difference worth detecting). For a one-sample t test D = μ ! μ0. For
a paired-sample t test D = μd. For an independent t test D = μ1 - μ2. These values are NOT calculated but come
from conjecture.
srepresents the standard deviation of the variable as estimated by s, sd, or sp depending on whether data are
from a single sample, paired samples, or independent samples.
Example: If you are trying to detect a mean difference of 18 for a variable with a standard deviation of 30, the
required sample size per group = .
(EpiCalc 2000: Right click the left tree and select Sample > Size > Single mean. Enter the mean difference
worth detecting (D) into the field labeled Mean, leave the field labeled Null hypothesis value as 0, and enter
s, sd, or sp into the field labeled SD. EpiCalc 2000 sample size calculations will be slightly smaller than those
provided by the above formula.
When testing multiple treatments with ANOVA I suggest you focus on the most important post hoc comparison of
means and use the above formula, perhaps using the square root of the Mean Square Within as your standard
deviation.
Power of a t Test (Comparison of Means)
Let f((z) represent the area under the curve to the left of z on a standard normal curve. For example, f(0) = 50%,
f(0.84) = 80%, and f(1.28) = 90%. (If this notation confuses you, draw a standard normal curve and place the z value
on the x axis. The area under the curve to the left of the Z point represents the probability you want to know.)
The power of a test (1!b) comparing means is approximately equal to:
where D denotes the expected mean difference (or difference worth detecting), n denotes the per group sample size,
and s denotes the standard deviation of the variable (e.g., s, sd, spooled, sw, etc., depending on your sampling scheme).
Example: A study of 30 pairs expects a mean difference of 2. The standard deviation of
the paired difference is 6.
How this works. Formula 19.5 assumes a sampling distribution of no difference (H0) and an alternative sampling
distribution of a difference (H1). Let critical value c determines the point at which you will reject H0. The power of the
test is the area under the alternative curve beyond c (Fig., below).
Estimating A Single Proportion
To calculate a 95% confidence interval for proportion p with margin of error d use a sample of size
where q = 1 ! p.
Examples: To calculate a 95% confidence interval for p that is expected to be about 50% (0.50) with a margin of error
(d) no more than 0.05, n = (1.96²)(.50)(1!0.50)/(.052) @ 384. To attain margin of error d = 0.03, n =
(1.96²)(0.50)(1!0.50)/(.032) @ 1067.
This method requires you to enter a value for p, which is exactly what you want to estimate This bothered me as a
student but is merely part of improving the accuracy of your estimate—one estimate begets a better estimate. If no
estimate of p is available, assume p = 0.50 to obtain a sample that is big enough to ensure precision.
EpiCalc 2000: Right-click the left-hand tree and select Sample > Precision > Single Proportion.
Enter p in the form of a percentage into the field labeled Proportion (%) and enter d in the form of a percentage
into the field labeled Precision (+/!).
Testing Two Proportions Based on a Cohort or Cross-Sectional Sample
Use EpiCalc 2000 > Size > Two Proportions when testing H0: RR = 1. Enter the significance level of
the test, required power, expected incidence proportion or prevalence in the exposed group (in the form of a %) in the
field labeled Proportion 1 (%), and the expected incidence proportion or prevalence in the nonexposed group
in the field labeled Proportion 2 (%).
Example: In testing H0: RR = 1 at a = .05 (two-sided) with power = 80% while assuming an incidence of 10% in the
exposed group and the incidence of 5% in the nonexposed group, you’ll need 433 people per group.
Testing an Odds Ratio from A Case-Control Study
Use EpiCalc 2000 > Size > Case-Control Study when testing data from a case-control study (H0:
OR = 1). Enter the significance level of the test, required power, Ratio of cases to controls, the odds
ratio worth detecting (OR to detect), and expected “prevalence” of exposure in the source population
(“controls”) in the field labeled Proportion (%) controls exposed.
Example: Suppose you test H0: OR = 1 at a = .05 (two-sided) with power = 80% using a 1:1 ratio of cases to controls
while looking for an odds ratio of 2. You assume the prevalence of exposure in the source population (controls) is
25%. EpiCalc 2000 determines you’ll need 151 cases and 151 controls in your study.
icchina 发表于 2012-1-19 00:21 static/image/common/back.gif
有没有epicalc 2000 for Mac的？
exe文件，我的电脑不能使用的。
非常抱歉，胡教授。找了半天，没有找到支持MAC的版本。{:1_4:} icchina 发表于 2012-1-19 00:21 static/image/common/back.gif
有没有epicalc 2000 for Mac的？
exe文件，我的电脑不能使用的。
美国CDC极力推荐的EPI INFO您能装吗？http://wwwn.cdc.gov/epiinfo/
类似，但是功能更强大些。 icchina 发表于 2012-1-19 00:21 static/image/common/back.gif
有没有epicalc 2000 for Mac的？
exe文件，我的电脑不能使用的。
What is Epi Info™?
Physicians, nurses, epidemiologists, and other public health workers lacking a background in information technology often have a need for simple tools that allow the rapid creation of data collection instruments and data analysis, visualization, and reporting using epidemiologic methods. Epi Info™, a suite of lightweight software tools, delivers core ad-hoc epidemiologic functionality without the complexity or expense of large, enterprise applications.
Epi Info™ is easily used in places with limited network connectivity or limited resources for commercial software and professional IT support. Epi Info™ is flexible, scalable, and free while enabling data collection, advanced statistical analyses, and geographic information system (GIS) mapping capability.
Since its initial release, Epi Info™ users have self-registered in over 181 countries covering all continents including Antarctica. Epi Info™ has been translated in more than 13 languages.
More than one million users are estimated.
EDUCATION
Epi Info™ is a key component in public health education at colleges, universities, and other schools of public health around the world.
COLLABORATION
Epi Info™ encourages collaboration between local, national, and international partners using Epi Info™ state and territorial epidemiologists; national centers, institutes, and government offices; and foreign ministries of health and United Nations World Health Organization constituents.
INNOVATION
Epi Info™ is dedicated to enabling the innovation and leadership required to improve public health through informatics.
How is Epi Info™ Used?
Epi Info™ is used worldwide for the rapid assessment of disease outbreaks; for the development of small to mid-sized disease surveillance systems; as ad hoc components integrated with other large scale or enterprise-wide public health information systems; and in the continuous education of public health professionals learning the science of epidemiology, tools, and techniques.
The MakeView module of Epi Info™ allows users to create questionnaires and data entry forms called Views in Epi Info™. With MakeView, users place questions and data entry fields on one or many pages of a View and tailor the data entry process with conditional skip patterns, data validation, and custom calculations programmed by the user using MakeView's Check Code.
The Enter module of Epi Info™ automatically creates the database from the questionnaire in MakeView. Users enter data, modify existing data, or search for records. With Enter, the Views are displayed and users perform the data entry while the Check Code validates the data or performs any automatic calculations that were specified in MakeView.
The Analysis module is used to read and analyze data entered with the Enter module or data imported from 24 different data formats. Epidemiologic statistics, tables, graphs, and maps are produced with simple commands such as READ, FREQ, LIST, TABLES, GRAPH, and MAP. As each command is run, it is saved to the program editor where it can be customized and saved, shared, and used in the future as data are revised.
The Epi Report module is a user-friendly tool to create professional custom reports that include results from the Analysis output. Epi Report can combine Analysis output with data from Enter as well as other sources such as Access or SQL Server. Reports can be saved as HTML files for easy distribution or web publishing.
The Epi Map module displays geographic maps with data from Epi Info. Epi Map is built around the Environmental Systems Research Institute (ESRI) MapObjects software. Epi Map displays shapefiles containing the geographic boundaries layered with data results from the Analysis module
帖子很给力，工具很有用，谢谢蓝鱼斑斑了 这个软件很好，谢谢草蓝鱼版主。 蓝鱼你太强啦，惭愧啊{:1_10:} 好软件，谢谢草蓝鱼版主。 为什么我安装不了呢？ 很好很强大！顶一个先！ 先下载下来，有时间了再慢慢琢磨。谢谢提供！ 谢谢blue fish分享，先下载收藏，以后肯定能用得上{:1_14:} 先下载再慢慢琢磨，再次感谢超版的倾情奉献！ 才看到这么好的东东，谢谢鱼儿斑斑。
由于不懂统计学，有个问题想请教鱼儿斑斑：这个小软件能进行fisher确切概率法计算吗？ 阳光 发表于 2012-3-18 16:39 static/image/common/back.gif
才看到这么好的东东，谢谢鱼儿斑斑。
由于不懂统计学，有个问题想请教鱼儿斑斑：这个小软件能进行fisher确 ...
可以的。他会给出不同算法的P值，根据N总和T选择不同的统计量。 先下载了，慢慢学习琢磨，谢谢版主提供。
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