ABSTRACT
The purpose of this paper was to introduce the χ2 test for the data of four-fold tables collected from the cohort design， the hypothesis test and interval estimation of relative risk， and the implementation of SAS and R software. In view of the characteristics of cohort design， the concept of relative risk， hypothesis testing and interval estimation were emphasized. It was given that the interpretation of the results calculated by SAS and R software， as well as the statistical and professional conclusions.
ABSTRACT
The purpose of this article was to introduce the χ2 test for the data of four-fold tables collected from the cross-sectional design and the realization of SAS and R software. Specifically， three methods were introduced， namely " Pearson΄s χ2 test"， "corrected Pearson΄s χ2 test" and "likelihood ratio χ2 test". The contents involved the test hypotheses， calculation principles and formulas， prerequisites， implementation of SAS and R software， interpretation of results and statement of conclusions of the aforementioned three statistical analysis methods.
ABSTRACT
The purpose of this paper was to introduce the McNemar΄s χ2 test and SAS and R software implementation of four-fold table data collected from the matched pairs design. Firstly， it was proposed that there were three situations for the data of four-fold table of the paired design， namely ①the data of paired design four-fold table with the special "gold standard" was worthy of statistical analysis； ②the data of four-fold table of the paired design without the special "gold standard" was not worthy of statistical analysis； ③the data of four-fold table collected from the matched pairs design with implicit "gold standard" was worthy of statistical analysis. Secondly， taking the "problems and data" in the first case as the object of statistical analysis， SAS and R software were used to analyze the differences， the calculation results were given and explained， and the statistical and professional conclusions were also made.
ABSTRACT
The purpose of this paper was to introduce the CMH χ2 test and SAS software implementation of the three kinds of R×C contingency table data. The first type was called “two-way unordered R×C contingency table data”. The CMH χ2 test corresponding to this type of data was essentially the Pearson’s χ2 test. The second type was called “R×C contingency table data with an ordinal outcome variable”. The CMH χ2 test corresponding to this kind of data was essentially a rank sum test. The third type was called “R×C contingency table data which was of two ordinal variables with different attributes”. The CMH χ2 test corresponding to the data was essentially Pearson’s correlation analysis or Spearman’s rank correlation analysis. When there were 1 or 2 “ordinal variables” in the R×C contingency table data， it was necessary to “assign or score” the ordinal variables before performing statistical analysis. In the FREQ procedure of SAS/STAT， there were four scoring methods. With different scoring approach， both the expression form and the calculation results of CMH χ2 test statistics could change accordingly.
ABSTRACT
The purpose of this paper was to introduce the linear trend χ2 tests for the data of the two kinds of one-way ordinal two-dimensional contingency tables and the implementation of SAS and R software. The two one-way ordered two-dimensional contingency tables referred to the “R×2 contingency table” with R values ordinal variable as the cause variable and the “2×C contingency table”with C values ordinal variable as the outcome variable. Their linear trend tests required the use of the Cochran-Armitage’s linear trend χ2 test and the Lee’s linear trend χ2 test， respectively.
ABSTRACT
The purpose of this article was to introduce the χ2 test and SAS and R software implementation of three kinds of two-way unordered two-dimensional contingency table data except the four-fold table data. The three kinds of the tables referred to the two-way unordered “R×2”“2×C” and “R×C” （both R and C were greater than 2） contingency tables. Generally speaking， the purpose of analyzing them was to test whether the two attribute variables in the contingency table were independent. When certain prerequisites were met， the simple statistical analysis method that could be used was the χ2 test， when the specific prerequisites were not met， the Fisher’s exact test， which required the large amount of calculation， should be selected.
ABSTRACT
The purpose of this paper was to introduce the χ2 test for the data of four-fold tables collected from the case-control design， the hypothesis test and interval estimation of odds ratio， and the implementation of SAS and R software. In view of the characteristics of case-control design， the concept of odds ratio， hypothesis testing and interval estimation were emphasized. It was given that the interpretation of the results calculated by SAS and R software， as well as the statistical conclusion and professional.
ABSTRACT
Objective To use Excel worksheet function to achieve statistical analysis of the fourfold table qualitative data,and to improve knowledge of the.majority of researchers on the statistical capabilities of Excel.Methods The result of actual research published in Chinese Journal of Endemiology was the data source,and statistical analysis results of fourfold table data from Excel and from SAS software were contrasted.Results The worksheet function of Excel could realize the analysis fourfold table data chi-square test,obtained an accurate P values,but not just P ＞ 0.05 or P ＜ 0.05.The results of chi-square test of Excel were the same as the results from SAS software,but Excel could not obtain probability value of fisher exact probability.Conclusion As a dependent statistical analysis software,Excel is an easy to learn,easy to use,efficient and a good helper.In the absence of professional statistical software,Excel can be used to achieve data statistical analysis.
ABSTRACT
In order to improve the production of agro-antibiotic 2-16,the producing strain(Streptomyces ahygroscopicus var.huangshanensis) was treated by protoplast regeneration,ultraviolet radiation,NTG mutagenesis and low energy C~(+) ion implantation.At last,a high-yield strain No.515 was obtained.The production of ~()No.515 was increased by 223.10%.By using Plackett-Burman design and Response Surface Analysis provided by SAS software,the cultivation condition of No.515 was optimized.The amount of agro-antibiotic 2-16 was increased by 38.53% when the strain No.515 was cultivated in the optimum medium instead of the initial one.