On the Mathematical Significance of the Similarity Index of Ochiai as a Measure for Biogeographical Habitats

1991 ◽  
Vol 39 (2) ◽  
pp. 143 ◽  
Author(s):  
HC Bolton
Keyword(s):  
Null Hypothesis ◽  
Hypothesis Test ◽  
Similarity Index ◽  
Critical Value ◽  
Critical Values ◽  
Geometrical Interpretation ◽  
Recent Survey ◽  
Mathematical Significance ◽  
Similarity Indices ◽  
Analyse Data

A recent survey of similarity indices by Hubalek has shown that the index due to Ochiai is one of the few satisfying rather stringent conditions. It is shown that the Ochiai index has a geometrical interpretation that can be exploited to yield a critical value for separability of two habitats on the basis of their avifauna. This critical value is used to analyse data on bird habitats and is compared with the results of a null hypothesis test on the data. In addition, use is made of the indices of Jaccard and Sokal & Michener. When the null test is used at the 5% level, all three indices agree in separating the habitats. The presence of a critical value of the Ochiai index gives it an advantage. A table of critical values is given for various numbers of species.

scholarly journals Detecting Heterogeneity of Substitution Along DNA and Protein Sequences

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 589-602 ◽  
Author(s):  
Peter J E Goss ◽  
R C Lewontin
Keyword(s):  
Null Hypothesis ◽  
Nonuniform Distribution ◽  
Critical Values ◽  
Third Order ◽  
Variance Test ◽  
Data Set ◽  
Significance Level ◽  
Uniformly Most Powerful Test ◽  
Interval Lengths ◽  
Uniformly Most Powerful

Abstract Regions of differing constraint, mutation rate or recombination along a sequence of DNA or amino acids lead to a nonuniform distribution of polymorphism within species or fixed differences between species. The power of five tests to reject the null hypothesis of a uniform distribution is studied for four classes of alternate hypothesis. The tests explored are the variance of interval lengths; a modified variance test, which includes covariance between neighboring intervals; the length of the longest interval; the length of the shortest third-order interval; and a composite test. Although there is no uniformly most powerful test over the range of alternate hypotheses tested, the variance and modified variance tests usually have the highest power. Therefore, we recommend that one of these two tests be used to test departure from uniformity in all circumstances. Tables of critical values for the variance and modified variance tests are given. The critical values depend both on the number of events and the number of positions in the sequence. A computer program is available on request that calculates both the critical values for a specified number of events and number of positions as well as the significance level of a given data set.

scholarly journals Role of thermal field in entanglement harvesting between two accelerated Unruh-DeWitt detectors

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Dipankar Barman ◽  
Subhajit Barman ◽  
Bibhas Ranjan Majhi
Keyword(s):  
Mutual Information ◽  
Critical Point ◽  
Thermal Field ◽  
Narrow Range ◽  
Critical Value ◽  
Critical Values ◽  
Parallel Motion ◽  
Field Temperature ◽  
The Right

Abstract We investigate the effects of field temperature T(f) on the entanglement harvesting between two uniformly accelerated detectors. For their parallel motion, the thermal nature of fields does not produce any entanglement, and therefore, the outcome is the same as the non-thermal situation. On the contrary, T(f) affects entanglement harvesting when the detectors are in anti-parallel motion, i.e., when detectors A and B are in the right and left Rindler wedges, respectively. While for T(f) = 0 entanglement harvesting is possible for all values of A’s acceleration aA, in the presence of temperature, it is possible only within a narrow range of aA. In (1 + 1) dimensions, the range starts from specific values and extends to infinity, and as we increase T(f), the minimum required value of aA for entanglement harvesting increases. Moreover, above a critical value aA = ac harvesting increases as we increase T(f), which is just opposite to the accelerations below it. There are several critical values in (1 + 3) dimensions when they are in different accelerations. Contrary to the single range in (1 + 1) dimensions, here harvesting is possible within several discrete ranges of aA. Interestingly, for equal accelerations, one has a single critical point, with nature quite similar to (1 + 1) dimensional results. We also discuss the dependence of mutual information among these detectors on aA and T(f).

New similarity index for crystal structure determination from X-ray powder diagrams

2005 ◽  
Vol 38 (6) ◽  
pp. 861-866 ◽  
Author(s):  
Detlef Walter Maria Hofmann ◽  
Ludmila Kuleshova
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Structure Prediction ◽  
Similarity Index ◽  
Crystal Structure Determination ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Organic Pigments ◽  
Structure Solution ◽  
Similarity Indices

A new similarity index for automated comparison of powder diagrams is proposed. In contrast to traditionally used similarity indices, the proposed method is valid in cases of large deviations in the cell constants. The refinement according to this index closes the gap between crystal structure prediction and automated crystal structure determination. The opportunities of the new procedure have been demonstrated by crystal structure solution of un-indexed powder diagrams of some organic pigments (PY111, PR181 and Me-PR170).

scholarly journals Applying shadowing technique to improve students' listening achievement

2020 ◽  
Vol 5 (1) ◽  
pp. 47-56
Author(s):  
Fitri Maini ◽  
Rachmanita
Keyword(s):  
Null Hypothesis ◽  
Sampling Method ◽  
Critical Value ◽  
T Test ◽  
Control Group ◽  
Tenth Graders ◽  
Tenth Grade ◽  
Quasi Experimental ◽  
The Mean ◽  
Experimental Group

This study tried find the students’ improvement in listening achievement after having taught by using the shadowing technique. The method used was a quasi-experimental that involved two groups, namely the control group and experimental group. The population of this study was all the tenth graders of SMA Negeri 3 Unggulan Kayuagung with a total number of 198 tenth graders. Purposive sampling method was applied to select the sample involved 72 tenth graders. In collecting the data, try out the test was used to get the desirable questions that would be used in the pretest and posttest to both groups in the control and experimental group. To verify the hypothesis, the normality and homogeneity of the data were firstly analyzed before being continued to be analyzed by using a t-test. Based on the result of data analysis in an independent sample t-test, there were some findings found. First, the mean score of a posttest (75.56) in the experimental group was higher than the pretest (69.03) in the control group. Secondly, the value of tobtained was 2.77 at the significant level of p<0.05 in two-tailed testing with df = 70, the critical value of ttable was 1.99. Since the value of tobtained was higher than ttable, the null hypothesis (Ho) was rejected and the research hypothesis was accepted. In conclusion, it showed that the shadowing technique could improve the tenth-grade students’ listening achievement at SMA Negeri 3 Unggulan Kayuagung.

scholarly journals Genetic Variation among and within United States Collard Cultivars and Landraces as Determined by Randomly Amplified Polymorphic DNA Markers

1996 ◽  
Vol 121 (3) ◽  
pp. 374-379 ◽  
Author(s):  
Mark W. Farnham
Keyword(s):  
Genetic Variation ◽  
Dna Markers ◽  
Crop Improvement ◽  
Similarity Index ◽  
Randomly Amplified Polymorphic Dna ◽  
Brussels Sprouts ◽  
Breeding Lines ◽  
Intrapopulation Variation ◽  
Similarity Indices ◽  
Systematic Collection

A collection of collard (Brassica oleracea L., Acephala group) germplasm, including 13 cultivars or breeding lines and 5 landraces, was evaluated using randomly amplified polymorphic DNA (RAPD) markers and compared to representatives of kale (Acephala group), cabbage (Capitata group), broccoli (Italica group), Brussels sprouts (Gemmifera group), and cauliflower (Botrytis group). Objectives were to assess genetic variation and relationships among collard and other crop entries, evaluate intrapopulation variation of open-pollinated (OP) collard lines, and determine the potential of collard landraces to provide new B. oleracea genes. Two hundred nine RAPD bands were scored from 18 oligonucleotide decamer primers when collard and other B. oleracea entries were compared. Of these, 147 (70%) were polymorphic and 29 were specific to collard. Similarity indices between collard entries were computed from RAPD data and these ranged from 0.75 to 0.99 with an average of 0.83. Collard entries were most closely related to cabbage (similarity index = 0.83) and Brussels sprouts entries (index = 0.80). Analysis of individuals of an OP cultivar and landrace indicated that intrapopulation genetic variance accounts for as much variation as that observed between populations. RAPD analysis identified collard landraces as unique genotypes and showed them to be sources of unique DNA markers. The systematic collection of collard landraces should enhance diversity of the B. oleracea germplasm pool and provide genes for future crop improvement.

scholarly journals THE EFFECT OF USING EDMODO APPLICATION ON THE STUDENTS’ WRITING SKILL OF ANALYTICAL EXPOSITION TEXT AT SMAN 4 PALANGKA RAYA

2021 ◽  
Vol 4 (2) ◽  
pp. 17
Author(s):  
Enggal Pinanggih ◽  
Ristati Ristati ◽  
Wahyuningsih Usadiati
Keyword(s):  
Null Hypothesis ◽  
Data Distribution ◽  
Critical Value ◽  
T Test ◽  
Teaching English ◽  
Writing Ability ◽  
Writing Test ◽  
Writing Skill ◽  
Dependent Sample ◽  
T Distribution

This research was conducted to find out the effect using Edmodo application on the students’ writing skill of analytical exposition text at SMAN 4 Palangka Raya. Data of the students score of writing Analytical Exposition text was collected using writing test, and the hypothesis testing was examined based on t-test for normally because the data distribution was normal. A test in form of writing analytical exposition text was used the instrument to collect the data needed. Then, the data were analyzed by using parametric statistic dependent sample T – test because the data were normally distributed. The writer took conclusion based on statistical result. The result of this research shows that the critical value for students T distribution was 1.734 the critical value t0 was t05 {19} = 1.729. Because 1.734 is greater than 1.729, null hypothesis was rejected. Thus, it can be concluded that there was significant effect of using Edmodo Application in writing Analytical Exposition Text gained by eleventh grade of SMAN 4 Palangka Raya. Thus, Edmodo Application had been successful in improving students’ writing ability of Analytical Exposition text. The researcher suggest that the teacher should provide an appropriate media in teaching English, especially for Analytical Exposition Text and made Edmodo Application as reference to him/her to use it for making students’ attracted to the material.

An abundance- and morphology-based similarity index

Paleobiology ◽  
2021 ◽  
pp. 1-18
Author(s):  
Daniel G. Dick ◽  
Marc Laflamme
Keyword(s):  
River Flow ◽  
Similarity Index ◽  
Ecological Gradients ◽  
Jaccard Similarity ◽  
Real World Data ◽  
Large Component ◽  
Morphological Gradient ◽  
Random Samples ◽  
Similarity Indices ◽  
General Method

Abstract Classic similarity indices measure community resemblance in terms of incidence (the number of shared species) and abundance (the extent to which the shared species are an equivalently large component of the ecosystem). Here we describe a general method for increasing the amount of information contained in the output of these indices and describe a new “soft” ecological similarity measure (here called “soft Chao-Jaccard similarity”). The new measure quantifies community resemblance in terms of shared species, while accounting for intraspecific variation in abundance and morphology between samples. We demonstrate how our proposed measure can reconstruct short ecological gradients using random samples of taxa, recognizing patterns that are completely missed by classic measures of similarity. To demonstrate the utility of our new index, we reconstruct a morphological gradient driven by river flow velocity using random samples drawn from simulated and real-world data. Results suggest that the new index can be used to recognize complex short ecological gradients in settings where only information about specimens is available. We include open-source R code for calculating the proposed index.

scholarly journals Impact of humidity biases on light precipitation occurrence: observations versus simulations

2018 ◽  
Author(s):  
Sophie Bastin ◽  
Philippe Drobinski ◽  
Marjolaine Chiriaco ◽  
Olivier Bock ◽  
Romain Roehrig ◽  
...  
Keyword(s):  
Land Surface ◽  
Climate Models ◽  
Regional Climate ◽  
Strong Dependence ◽  
Mediterranean Area ◽  
Critical Value ◽  
Critical Values ◽  
Frequency Of Occurrence ◽  
The Impact ◽  
Light Precipitation

Abstract. This work uses a network of GPS stations over Europe from which a homogenised integrated water vapor (IWV) dataset has been retrieved, completed with colocated temperature and precipitation measurements over specific stations to i) estimate the biases of six regional climate models over Europe in terms of humidity; ii) understand their origins; iii) and finally assess the impact of these biases on the frequency of occurrence of precipitation. The evaluated simulations have been performed in the framework of HYMEX/Med-CORDEX programs and cover the Mediterranean area and part of Europe at horizontal resolutions of 50 to 12 km. The analysis shows that models tend to overestimate the low values of IWV and the use of the nudging technique reduces the differences between GPS and simulated IWV. Results suggest that physics of models mostly explain the mean biases, while dynamics affects the variability. The land surface/atmosphere exchanges affect the estimation of IWV over most part of Europe, especially in summer. The limitations of the models to represent these processes explain part of their baises in IWV. However, models correctly simulate the dependance between IWV and temperature, and specifically the deviation that this relationship experiences regarding the Clausius-Clapeyron law after a critical value of temperature (Tbreak). The high spatial variability of Tbreak indicates that it has a strong dependence on local processes which drive the local humidity sources. This explains why the maximum values of IWV are not necessarely observed over warmer area, that are often dry area. Finally, it is shown over SIRTA observatory (near Paris) that the frequency of occurrence of light precipitation is strongly conditioned by the biases in IWV and by the precision of the models to reproduce the distribution of IWV as a function of the temperature. The results of the models indicate that a similar dependence occurs in other areas of Europe, especially where precipitation has a predominantly convective character. According to the observations, for each range of temperature, there is a critical value of IWV from which precipitation picks up. The critical values and the probability to exceed them are simulated with a bias that depends on the model. Those models which present too often light precipitation generally show lower critical values and higher probability to exceed them.

scholarly journals Integration of AHP and Regression Analysis in Forecasting Attendance in a Movie Theater

2020 ◽  
Vol 12 (2) ◽  
pp. 14
Author(s):  
Hossein Jamshidi
Keyword(s):  
Regression Analysis ◽  
Analytical Hierarchy Process ◽  
Null Hypothesis ◽  
Hypothesis Test ◽  
Strong Predictor ◽  
Time Of Day ◽  
Contributing Factors ◽  
Statistical Software ◽  
Movie Theater ◽  
Hierarchy Process

Forecasting the number of attendees in a motion picture has often been considered a wild guess since there are many factors or variables involved in forecasting the numbers.  There are many contributing factors to consider when attempting forecasting theatre attendance. Among many possible variables the ones with the most significant impact that are considered in this study are; the day that movie is playing, the time of day that movie plays, the ranking of the movie, the genre of movie, the length of time that the movie has been released and finally whether school is in or out. For the most part, these are quantifiable measures and thus should be able to derive an accurate forecasting module. At first, the aim of this study is to compare all the variables by the decision maker based on the Analytical Hierarchy Process (AHP) and to rank the variables based on the importance according to the AHP process. Once the variables are set, the regression analysis is applied to forecast attendance in a movie theater.  Multiple regression analysis is used in this study based on a sample of 711 observations. Using SPSS statistical software, a model is developed to forecast the number of attendees and the model provides R2 = 0.760, which is a strong predictor. Finally, the hypothesis test is conducted to verify the accuracy of the regression model with the actual data and even with a = 0.10 the null hypothesis could not be rejected.

Response to Technical Comment on Rickles, Heppen, Allensworth, Sorensen, and Walters (2018)

2019 ◽  
Vol 48 (4) ◽  
pp. 241-243
Author(s):  
Jordan Rickles ◽  
Jessica B. Heppen ◽  
Elaine Allensworth ◽  
Nicholas Sorensen ◽  
Kirk Walters
Keyword(s):  
Confidence Intervals ◽  
Null Hypothesis ◽  
Hypothesis Test ◽  
Hypothesis Tests

In response to the concerns White raises in his technical comment on Rickles, Heppen, Allensworth, Sorensen, and Walters (2018), we discuss whether it would have been appropriate to test for nominally equivalent outcomes, given that the study was initially conceived and designed to test for significant differences, and that the conclusion of no difference was not solely based on a null hypothesis test. To further support the article’s conclusion, confidence intervals for the null hypothesis tests and a test of equivalence are provided.

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