scholarly journals Software to calculate sample size for different designs, including targeted and non‐targeted surveys, as well as actual allocation and selection of sample units

2016 ◽  
Vol 13 (7) ◽  
Author(s):  
Tobias Verbeke ◽  
Machteld Varewyck
Keyword(s):  
Sample Size ◽  
Calculate Sample Size ◽  
Selection Of

data a; * significance level; a=0.05; * variance of difference of two observations on the log scale; * sigmaW = within-subjects standard deviation; sigmaW=0.355; s=sqrt(2)*sigmaW; * total number of subjects (needs to be a multiple of 2); n=58; * error degrees of freedom for AB/BA cross-over with n subjects in total; n2=n-2; * ratio = mu_T/mu_R; ratio=1.00; run; data b; set a; * calculate power; t1=tinv(1-a,n-2); t2=-t1; nc1=(sqrt(n))*((log(ratio)-log(0.8))/s); nc2=(sqrt(n))*((log(ratio)-log(1.25))/s); df=(sqrt(n-2))*((nc1-nc2)/(2*t1)); prob1=probt(t1,df,nc1); prob2=probt(t2,df,nc2); answer=prob2-prob1; power=answer*100; run; proc print data=b; run; As an example of using this SAS code, suppose µ = 1, σ = 0.355, α = 0.05 and n = 58. The power (as a percentage) is calculated as 90.4. The required number of subjects to achieve a given power can easily be obtained by trial and error using a selection of values of n. An alternative approach is to use trial and error directly on the sample size n for a given power. For more on this see Phillips (1990) and Diletti et al. (1991), for example. 7.4 Individual bioequivalence As noted in Section 7.1, individual bioequivalence (IBE) is a criterion for deciding if a patient who is currently being treated with R can be

2003 ◽  
pp. 362-362
Keyword(s):  
Standard Deviation ◽  
Sample Size ◽  
Degrees Of Freedom ◽  
Trial And Error ◽  
Significance Level ◽  
Individual Bioequivalence ◽  
Alternative Approach ◽  
Within Subjects ◽  
Log Ratio ◽  
Selection Of

scholarly journals Resampled dimensional reduction for feature representation in machine learning

2021 ◽  
Author(s):  
Herdiantri Sufriyana ◽  
Yu Wei Wu ◽  
Emily Chia-Yu Su
Keyword(s):  
Machine Learning ◽  
Parameter Estimation ◽  
Prediction Model ◽  
Sample Size ◽  
Dimensional Reduction ◽  
Latent Variables ◽  
Feature Representation ◽  
Estimated Parameters ◽  
Representation Technique ◽  
Selection Of

Abstract We aimed to provide a resampling protocol for dimensional reduction resulting a few latent variables. The applicability focuses on but not limited for developing a machine learning prediction model in order to improve the number of sample size in relative to the number of candidate predictors. By this feature representation technique, one can improve generalization by preventing latent variables to overfit data used to conduct the dimensional reduction. However, this technique may warrant more computational capacity and time to conduct the procedure. The key stages consisted of derivation of latent variables from multiple resampling subsets, parameter estimation of latent variables in population, and selection of latent variables transformed by the estimated parameters.

scholarly journals How to Calculate Sample Size and Why

2013 ◽  
Vol 5 (3) ◽  
pp. 235 ◽  
Author(s):  
Jeehyoung Kim ◽  
Bong Soo Seo
Keyword(s):  
Sample Size ◽  
Calculate Sample Size

Construction and selection of quick switching double-sampling system: sample size tightening

1995 ◽  
Vol 22 (1) ◽  
pp. 105-119 ◽  
Author(s):  
S. Devaraj Arumainayagam ◽  
V. Soundararajan
Keyword(s):  
Sample Size ◽  
Double Sampling ◽  
Sampling System ◽  
Selection Of

scholarly journals Assessing terpene content variability of whitebark pine in order to estimate representative sample size

2013 ◽  
pp. 193-204
Author(s):  
Milena Stefanovic ◽  
Slobodanka Mitrovic ◽  
Dragica Obratov-Petkovic ◽  
Vera Vidakovic ◽  
Zorica Popovic ◽  
...  
Keyword(s):  
Sample Size ◽  
Representative Sample ◽  
Mean Value ◽  
Whitebark Pine ◽  
Initial Sample ◽  
Basic Set ◽  
Chemical Content ◽  
The Mean ◽  
Selection Of

In studies of population variability, particular attention has to be paid to the selection of a representative sample. The aim of this study was to assess the size of the new representative sample on the basis of the variability of chemical content of the initial sample on the example of a whitebark pine population. Statistical analysis included the content of 19 characteristics (terpene hydrocarbons and their derivates) of the initial sample of 10 elements (trees). It was determined that the new sample should contain 20 trees so that the mean value calculated from it represents a basic set with a probability higher than 95 %. Determination of the lower limit of the representative sample size that guarantees a satisfactory reliability of generalization proved to be very important in order to achieve cost efficiency of the research.

scholarly journals Effect of plot size and plant spatial arrangement on the efficiency of family selection in sugarcane

2021 ◽  
Vol 53 (2) ◽  
pp. 1-10
Author(s):  
Aparecido De Moraes ◽  
Matheus Henrique Silveira Mendes ◽  
Mauro Sérgio de Oliveira Leite ◽  
Regis De Castro Carvalho ◽  
Flávia Maria Avelar Gonçalves
Keyword(s):  
Sample Size ◽  
Bootstrap Method ◽  
Spatial Arrangement ◽  
Family Selection ◽  
Plot Size ◽  
Stalk Diameter ◽  
New Varieties ◽  
Selection Of ◽  
The Bootstrap Method ◽  
The Ideal

The purpose of this study was to identify the ideal sample size representing a family in its potential, to identify superior families and, in parallel, determine in which spatial arrangement they may have a better accuracy in the selection of new varieties of sugarcane. For such purpose, five families of full-sibs were evaluated, each with 360 individuals, in the randomized blocks design, with three replications in three different spacing among plants in the row (50 cm, 75 cm, and 100 cm) and 150 cm between the rows. To determine the ideal sample size, as well as the better spacing for evaluation, the bootstrap method was adopted. It was observed that 100 cm spacings provided the best average for the stalk numbers, stalk diameter and for estimated weight of stalks in the stool. The spacing of 75 cm between the plants allowed a better power of discrimination among the families for all characters evaluated. At this 75 cm spacing  was also possible to identify superior families with a sample of 30 plants each plot and 3 reps in the trial. Highlights The bootstrap method was efficient to determine the ideal sample size, as well as the best spacing for evaluation. The 75-cm spacing had the highest power of discrimination among families, indicating that this spacing is the most efficient in evaluating sugarcane families for selection purposes. From all the results and considering selective accuracy as the guiding parameter for decision making, the highest values obtained considering the number of stalks and weight of stalks in the stools were found at the 75-cm spacing.

Normality and Sample Size Do Not Matter for the Selection of an Appropriate Statistical Test for Two-Group Comparisons

Methodology ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 61-71 ◽  
Author(s):  
Antoine Poncet ◽  
Delphine S. Courvoisier ◽  
Christophe Combescure ◽  
Thomas V. Perneger
Keyword(s):  
Sample Size ◽  
Test Performance ◽  
Permutation Test ◽  
Bimodal Distribution ◽  
Error Rates ◽  
T Test ◽  
Sample Sizes ◽  
Whitney Test ◽  
Mann Whitney Test ◽  
Selection Of

Abstract. Many applied researchers are taught to use the t-test when distributions appear normal and/or sample sizes are large and non-parametric tests otherwise, and fear inflated error rates if the “wrong” test is used. In a simulation study (four tests: t-test, Mann-Whitney test, Robust t-test, Permutation test; seven sample sizes between 2 × 10 and 2 × 500; four distributions: normal, uniform, log-normal, bimodal; under the null and alternate hypotheses), we show that type 1 errors are well controlled in all conditions. The t-test is most powerful under the normal and the uniform distributions, the Mann-Whitney test under the lognormal distribution, and the robust t-test under the bimodal distribution. Importantly, even the t-test was more powerful under asymmetric distributions than under the normal distribution for the same effect size. It appears that normality and sample size do not matter for the selection of a test to compare two groups of same size and variance. The researcher can opt for the test that fits the scientific hypothesis the best, without fear of poor test performance.

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