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1.
There exist several formulae for sample sizes for testing the equivalence of binomial proportions which are based on approximations by the normal distribution. Quite often these formulae produce drastically different results. In this paper the validity of the approximate sample sizes is investigated with respect to the exact distributions.  相似文献   

2.
The available power tables for use in experimental design only serve for limited practical purposes, since they are restricted to very few levels of significance such as .01, .05, and .10. With these values, however, usually no correction for cumulating error probabilities, for example, by the Dunn-Bonferroni method, can be achieved, because (very) low values of a and sometimes even of α are necessary. Therefore, power tables are presented that encompass a wide range of different values for a (.0005 to .40), for power (.50 to .9995), and for 45 different values of the degrees of freedom for the numerator of the F ratio (u = 1 to 150). Four of the 16 tables are printed. Their use is demonstrated for some paradigmatic problems in univariate and multivariate analyses of variance and regression.  相似文献   

3.
Based on capture-mark-recapture sampling methods the problem of estimating unknown population size was considered. The sampling started with the assumption that at the beginning of the experiment all the individuals were unmarked, and the unmarked individuals caught in each sample will be marked and returned to the original population before the next sample is drawn. It is also assumed that the population is closed by birth, death, emigration and immigration. Using a general inverse sampling approach, the unknown population size N is estimated by a maximum likelihood estimator (MLE), and a simple form for approximate MLE is obtained. The probability function for S (the minimum number of samples required to be drawn to have L (L ≥ 1) samples, each of which contains at least one marked individual) and the form for E[S] are also obtained. In addition, corrections and improvements of some previous works in this field are given.  相似文献   

4.
In this paper, we shall study an alternative method of deriving Neyman's Optimum allocation of sample size to strata for simple random sampling which is intuitive and simple. In order to obtain this allocation, the within stratum standard deviations of the study variate are required which are unknown and hence are substituted by known quantities. We shall discuss the effects of deviations from the optimum allocation and other related problems.  相似文献   

5.
6.
ABSTRACT Cost considerations may be as important as precision when making survey-design choices, and the ability to accurately estimate survey costs will be essential if survey budgets become more constrained. We used data from a survey of ring-necked ducks (Aythya collaris) to illustrate how simple distance formulas can be used to construct a cost function for aerial quadrat surveys. Our cost function provided reasonable estimates of effort (hr) and costs, and allowed us to evaluate plot-size choices in terms of expected cost-precision tradeoffs. Although factors influencing costs in wildlife surveys can be complicated, we believe that cost functions deserve more attention and should be routinely considered in conjunction with traditional power analyses.  相似文献   

7.
In this paper (1) expressions (correct to n?2 terms) for biases, variances, and covariances of the estimators a and b of Hermite distribution with probability generating function Exp[a(t–1) + b(t–1)] are obtained for two mixed moment estimates; (2) for the biases and variance-covariances, approximate regions of the parameter space (a>0, b>0) have been outlined where a sample of size 100 can be considered as “safe” in the sense that contribution of second order terms in them is 5% of that from the first order term; (3) comparison of the biases and variance-covariances of these two sets of estimators are made with those for the moment estimators, maximum likelihood estimates and the even point estimators for a sample of size 100 using the terms up to order n?2; (4) the comparisons based on n?2 terms in (3) have not only provided information on the estimation procedures included in the Hermite distribution, but also demonstrated the importance of higher order terms in the sampling properties of the various alternative techniques for the Hermite distribution.  相似文献   

8.
Most mixed strain progeny from gene-knockout experiments typically originate from C57BL/6J and one of the 129 substrains, frequently 129S6/SvEvTac. The results of this behavioral survey suggest that C57BL/6J:129S6/SvEvTac mixed strain mice are amenable to behavioral testing. The variability in behavioral tasks for subjects arising from this mixed strain genetic background does not preclude screening with a battery of behavioral tests. With clues provided by a screen of mixed strain subjects, follow-up analyses with isogenic, congenic, or F1 hybrid animals may be targeted to specific behavioral themes.  相似文献   

9.
The council of the European Economic Communities has issued a directive (86/469/EEC) for the examination of animals and fresh meat for the presence of residues of several hormones, drugs and environmental pollutants. The purpose of this paper is to compare the method used by the EEC with a Bayesian approach to calculate necessary sample size using prior information in different situations (assuming Beta-, Normal- and Gamma-distribution for the prior distribution). It has been shown that the Bayesian approach requires significantly smaller sample sizes for all levels of inspection. Furthermore, an example is given in the examination of pigs for the presence of residues of drugs in pork.  相似文献   

10.
贺兰山保护区冬季岩羊集群特征的初步分析   总被引:8,自引:1,他引:8  
Group size and composition of blue sheep (Pseudois nayaur) were studied in the Helan Mountains, Ningxia Autonomous Region from November to December 2003. We scanned mountain slopes with binoculars and observed with 20 - 60 x spotting-scope. A total of 310 herds of blue sheep and 1 336 individuals were observed during the study period. Blue sheep were frequently seen in small herds of 2 to 8 individuals, which represent 94.8% of total herds observed. Herds consisting of 9 individuals or more represented 5.2%. The largest herd we observed numbered 51 individuals. Mean group size was 4.2 individuals. Blue sheep herds can be divided into three types: male herds (composed solely of males), female herds (consisting of females with or without juveniles of both sexes), and mixed herds (including adult males, females, and subadults). Among the 310 herds, female herds were counted 150 times (48.4%}, mixed herds 154 times (49.7%), and male berds 6 times (1.9%) . Of 1 336 blue sheep classified by sex and age, adults, subadults and juveniles composed 64.1%, 20.8%, and 15.1% respectively. The female: male ratio of adults was 1:0.73. The ratio of adult females to juveniles was 1:0.56, which is higher than the ratio recorded in spring ( 1:0.43) or summer ( 1:0.44). The results showed that the Helan Mountains State Nature Reserve has succeed in protecting blue sheep.  相似文献   

11.
Hidden Markov models were successfully applied in various fields of time series analysis, especially for analyzing ion channel recordings. The maximum likelihood estimator (MLE) has recently been proven to be asymptotically normally distributed. Here, we investigate finite sample properties of the MLE and of different types of likelihood ratio tests (LRTs) by means of simulation studies. The MLE is shown to reach the asymptotic behavior within sample sizes that are common for various applications. Thus, reliable estimates and confidence intervals can be obtained. We give an approximative scaling function for the estimation error for finite samples, and investigate the power of different LRTs suitable for applications to ion channels, including tests for superimposed hidden Markov processes. Our results are applied to physiological sodium channel data.  相似文献   

12.
糖基化作为一种常见的蛋白质翻译后修饰,对蛋白质的空间结构、生物功能等具有重要的影响.解析糖蛋白糖链结构有助于更清楚地认识糖蛋白及其功能.本研究建立了一种基于超滤膜富集血清中糖蛋白全N-连接糖链,并利用质谱技术对糖链结构进行分析的方法.根据糖蛋白及其糖链结构之间的分子质量差异,利用Millipore公司的10 ku超滤膜富集血清糖蛋白上酶解(PNGase F)释放的全N-连接糖链,并使用MALDI-TOF/TOF-MS解析糖链结构.通过该技术可以从血清中富集并鉴定到23种独特的N-连接的糖链结构,并且利用二级质谱进行了结构确认.该方法可以被用于从大量生物样本中富集糖蛋白全N-连接糖链,可以达到快速、高通量地解析糖蛋白N-连接糖链的目的.  相似文献   

13.
草鱼种群SSR分析中样本量及标记数量对遗传多度的影响   总被引:12,自引:0,他引:12  
利用45对微卫星分子标记(SSR),以草鱼(Ctenopharyngodon idellus)自然群体为实验材料,探讨野生群体遗传多样性研究中所需的最适样本量与标记量。实验设置6个样本量梯度,9个标记量梯度。对等位基因数(Na)、有效等位基因数(Ne)、观察杂合度(Ho)、期望杂合度(He)等遗传多样性指标的变化趋势进行统计分析。结果表明,样本量、微卫星标记的数量和多态性水平对群体遗传多样性均有较大的影响,其中等位基因数与样本量大小呈显著正相关,而杂合度随标记量的增多而剧烈波动。当取样量大于40,标记量大于25时,各遗传参数值趋于稳定。因此,在应用微卫星标记对水产动物自然群体的遗传学研究中,要根据所研究种类的特点,尽可能采样40尾以上,采用25个以上标记,避免由人为选择的偏差对群体遗传多样性水平的正确评估所造成的影响。同时根据上述研究结果,对陕西草鱼自然群体进行了遗传多样性的评估,结果显示该群体平均等位基因数(MNA)、平均有效等位基因数、平均观测杂合度、平均期望杂合度分别为7.26、4.21、0.73、0.68,认为该群体具有较高的遗传多样性。  相似文献   

14.
正交试验法优选三七茎叶中总黄酮的提取工艺   总被引:2,自引:2,他引:2  
目的:从三七茎叶中提取总黄酮。方法:采用正交试验法研究三七茎叶总黄酮的提取工艺,考察了浸提用水的pH值、浸提温度、浸提时间、浸提次数、液料比五个因素对三七茎叶总黄酮提取率的影响。结果:确立了三七茎叶总黄酮最佳提取条件为:用pH10的稀碱水作溶剂,液料比30:1,浸提温度为80℃,回流提取2次,提取时间为每次40min。  相似文献   

15.
以总黄酮解吸率和滤液中总黄酮含量为指标,通过正交实验设计优选大孔树脂分离纯化有柄石韦总黄酮的最佳工艺。结果表明,D-101型大孔树脂分离纯化总黄酮的优选工艺条件为:上样液质量浓度0.5 mg·mL-1,pH为6,洗脱剂乙醇浓度为50%,洗脱速率2 mL·min-1。该优化方法稳定可行,结果可靠,提取的滤液中总黄酮含量达76.40%。  相似文献   

16.
Quantification of liver regeneration is frequently based on determining the 5-bromo-2-deoxyuridine labeling index (BrdU-LI). The quantitative result is influenced by preanalytical, analytical, and postanalytical variables such as the region of interest (ROI). We aimed to present our newly developed and validated automatic computer-based image analysis system (AnalySIS-Macro), and to standardize the selection and sample size of ROIs. Images from BrdU-labeled and immunohistochemically stained liver sections were analyzed conventionally and with the newly developed AnalySIS-Macro and used for validation of the system. Automatic quantification correlated well with the manual counting result (r=0.9976). Validation of our AnalySIS-Macro revealed its high sensitivity (>90%) and specificity. The BrdU-LI ranged from 11% to 57% within the same liver (32.96 ± 11.94%), reflecting the highly variable spatial distribution of hepatocyte proliferation. At least 2000 hepatocytes (10 images at 200× magnification) per lobe were required as sample size for achieving a representative BrdU-LI. Furthermore, the number of pericentral areas should be equal to that of periportal areas. The combination of our AnalySIS-Macro with rules for the selection and size of ROIs represents an accurate, sensitive, specific, and efficient diagnostic tool for the determination of the BrdU-LI and the spatial distribution of proliferating hepatocytes. (J Histochem Cytochem 57:1075–1085, 2009)  相似文献   

17.
为了研制高效、安全、无污染的抗生素替代物作为断奶仔猪饲料添加剂,本研究观察了中药超微粉对21日龄断奶仔猪外周血白细胞分类和血清抗氧化功能的影响。结果表明,D7时,超微粉组MDA含量显著小于抗生素组和对照组(P<0.05),NO含量显著小于对照组(P<0.05);D14时,超微粉组NO含量显著大于抗生素组和对照组(P<0.05);D28时,超微粉组NEU计数和百分率及MON百分率均显著小于、LYM百分率显著大于对照组(P<0.05),N/L小于抗生素组(P>0.05)、显著小于对照组(P<0.05),SOD活性显著大于抗生素组和对照组(P<0.05),GSH活性显著大于对照组(P<0.05)。上述指标的变化,与该超微粉对断奶仔猪的防病促生长作用有一定联系。  相似文献   

18.
Gastropods Nucella heyseana were collected from 1999 to 2001 from different habitats in Vostok Bay (Sea of Japan). The spatial distribution, the seasonal and interannual dynamics, and the composition of aggregations of this mollusk were analyzed. In Vostok Bay, N. heyseana inhabits biotopes that are typical of this species and other members of the genus and sometimes forms aggregations with an unusually high density and biomass (up to 1690 spec/m2 and 3680 g/m2), thus exceeding 10–40 times the greatest values reported elsewhere for populations of the southern Kuril Islands and Pos'eta Bay (Sea of Japan). N. heyseana is a typical polyphagous predator, and its diet includes numerous species of the associated fauna of bivalve and gastropod mollusks (more than 30 species). The abundance, composition, and stability of local aggregations of N. heyseana are largely dependent on the abundance dynamics of its prey (primarily the most common species, such as Mytilus trossulus, Ruditapes philippinarum, Protothaca euglypta, and Littorina spp.). The opinion on the low density of N. heyseana in southern Primorye (Golikov, Kussakin, 1978) is probably based on a lack of information about the intertidal fauna of this region compared to the South Kuril Islands.  相似文献   

19.
We estimated the population size of the finless porpoise (Neophocaena phocaenoides) in Ariake Sound and Tachibana Bay of western Kyushu, southwestern Japan, from aerial sighting surveys using line transect methods. All 12 surveys were conducted from May 1993 to May 1994 (8 in Ariake Sound and 4 in Tachibana Bay). In addition to these, 14 surveys were also carried out to obtain information on porpoise occurrence in Tachibana Bay (5 surveys) and in neighboring Sumo Nada (5) and Yatsushiro Sound (4). In Ariake Sound, 225 porpoise groups (369 animals) were detected during all flights totalling 1,694.4 km. In Tachibana Bay, a total of 997.8 km was surveyed and 55 groups (290 animals) were sighted. However, no sightings were recorded in Sumo Nada (distance searched = 148.7 km) and Yatsushiro Sound (208.4 km). In Ariake Sound, few sightings were recorded from waters shallower than 5 m in depth. In Tachibana Bay all animals were detected from waters of less than 50 m depth. The population size was estimated as 1,983 animals in Ariake Sound (95% CI = 1,382-2,847), 1,110 in Tachibana Bay (95% CI = 642-1,920), and 3,093 in the 2 waters (1.3 individuals/km2, 95% CI = 2,278-4,201).  相似文献   

20.
The peanut (Arachis hypogaea L.) seeds harvested at the last stage of maturation were divided into five grades by size. The content of total protein, salt-soluble protein, arachin, conarachin I and 2s globulin in these seeds were measured. No obvious differences in germination percentage and the length of radicle and hypocotyl within 3d germination in dark were observed among the five grades of seeds. But there were significant differences in the seedling growth after two weeks of germination in light. There was a very close correlation between the storage protein in cotyledons and the seedling growth. When seeds germinated in light, the efficiency of mobilization of the salt-soluble protein in the cotyledons was higher than that in the cotyledons of the seeds germinating in dark. All of the salt-soluble protein in cotyledons was used up after 14d seedling growth in light. SDS-PAGE of salt-soluble protein showed that 23.5, 38.5 and 41 kD subunits of arachin were first mobilized during germination. The 18 kD subunits of arachin were not mobilized until the above-mentioned subunits were used up. The 60.5 kD subunit of conarachin I and 2s globulin were degradated within 2 to 3 days during germination.  相似文献   

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