scholarly journals Deviations between Contract Sums and Final Accounts: The Case of Capital Projects in Ghana

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Kofi Offei-Nyako ◽  
Leslie Cyprian Ohene Tham ◽  
Mark Bediako ◽  
Charles Dela Adobor ◽  
Richard Oduro Asamoah
Keyword(s):  
Sample Size ◽  
Cost Estimation ◽  
Null Hypothesis ◽  
Significance Test ◽  
Transport Infrastructure ◽  
Market Demand ◽  
Capital Projects ◽  
Coefficient Of Concordance ◽  
Level Of Agreement ◽  
Significant Factors

Cost estimation is particularly difficult, often leading to considerable deviations. For capital projects, especially transport infrastructure projects, deviations hover around an average of 28% of the estimated cost. There are several factors that cause these deviations between the final accounts and the contract sum. How these factors combine to cause deviations between the contract sum and the final account in recent times has been of great concern to construction managers and researchers alike. This study sought to identify the significant factors that result in deviations between contract sums and the final accounts of capital projects. Using a sample size of 45, comprising contractors, consultants, and clients, the factors identified using Relative Important Indices were “price fluctuations,” “late material delivery,” “changes in the scope of work,” “fluctuations in the market demand,” and “changes in design.” Using Kendall’s coefficient of concordance, a coefficient p value of 0.068 was obtained. As such, the null hypothesis was rejected as there was a level of agreement among the respondents. Again, based on a significance test run, 26 out of the 40 identified factors used for the analysis were seen to be significant in influencing the deviations between contract sums and final accounts figures.

scholarly journals Not Significant: What Now?

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Gerhard Marinell ◽  
Gabriele Steckel-Berger ◽  
Hanno Ulmer
Keyword(s):  
Sample Size ◽  
Random Sample ◽  
Null Hypothesis ◽  
Significance Test ◽  
Additional Information ◽  
A Value ◽  
Test Of Significance

In a classic significance test, based on a random sample with size , a value will be calculated at size aiming to reject the null hypothesis. The sample size , however, can retrospectively be divided into partial samples and a test of significance can be calculated for each partial sample. As a result, several partial samples will provide significant values whereas others will not show significant values. In this paper, we propose a significance test that takes into account the additional information from the values of the partial samples of a random sample. We show that the    values can greatly modify the results of a classic significance test.

The Numbers Will Love You Back in Return—I Promise

2016 ◽  
Vol 11 (4) ◽  
pp. 551-554 ◽  
Author(s):  
Martin Buchheit
Keyword(s):  
Sample Size ◽  
Null Hypothesis ◽  
Clinical Medicine ◽  
Statistical Significance ◽  
Significance Testing ◽  
Null Hypothesis Significance Testing ◽  
Sport Science ◽  
Size Dependent ◽  
Research Questions ◽  
Per Se

The first sport-science-oriented and comprehensive paper on magnitude-based inferences (MBI) was published 10 y ago in the first issue of this journal. While debate continues, MBI is today well established in sport science and in other fields, particularly clinical medicine, where practical/clinical significance often takes priority over statistical significance. In this commentary, some reasons why both academics and sport scientists should abandon null-hypothesis significance testing and embrace MBI are reviewed. Apparent limitations and future areas of research are also discussed. The following arguments are presented: P values and, in turn, study conclusions are sample-size dependent, irrespective of the size of the effect; significance does not inform on magnitude of effects, yet magnitude is what matters the most; MBI allows authors to be honest with their sample size and better acknowledge trivial effects; the examination of magnitudes per se helps provide better research questions; MBI can be applied to assess changes in individuals; MBI improves data visualization; and MBI is supported by spreadsheets freely available on the Internet. Finally, recommendations to define the smallest important effect and improve the presentation of standardized effects are presented.

scholarly journals A Critical Evaluation of the FBST ev for Bayesian Hypothesis Testing

2021 ◽  
Author(s):  
Alexander Ly ◽  
Eric-Jan Wagenmakers
Keyword(s):  
Hypothesis Testing ◽  
Null Hypothesis ◽  
Alternative Hypothesis ◽  
Critical Evaluation ◽  
Significance Test ◽  
Bayesian Hypothesis Testing ◽  
Absence Of Evidence ◽  
Evidence Of Absence ◽  
Foregone Conclusion

AbstractThe “Full Bayesian Significance Test e-value”, henceforth FBST ev, has received increasing attention across a range of disciplines including psychology. We show that the FBST ev leads to four problems: (1) the FBST ev cannot quantify evidence in favor of a null hypothesis and therefore also cannot discriminate “evidence of absence” from “absence of evidence”; (2) the FBST ev is susceptible to sampling to a foregone conclusion; (3) the FBST ev violates the principle of predictive irrelevance, such that it is affected by data that are equally likely to occur under the null hypothesis and the alternative hypothesis; (4) the FBST ev suffers from the Jeffreys-Lindley paradox in that it does not include a correction for selection. These problems also plague the frequentist p-value. We conclude that although the FBST ev may be an improvement over the p-value, it does not provide a reasonable measure of evidence against the null hypothesis.

scholarly journals A Comparison Study of Goodness of Fit Tests of Logistic Regression in R: Simulation and Application to Breast Cancer Data

2020 ◽  
pp. 50-59
Author(s):  
El-Housainy A. Rady ◽  
Mohamed R. Abonazel ◽  
Mariam H. Metawe’e
Keyword(s):  
Breast Cancer ◽  
Logistic Regression ◽  
Sample Size ◽  
Null Hypothesis ◽  
Goodness Of Fit ◽  
Quadratic Term ◽  
Breast Cancer Dataset ◽  
Cancer Data ◽  
Interaction Term ◽  
Test Package

Goodness of fit (GOF) tests of logistic regression attempt to find out the suitability of the model to the data. The null hypothesis of all GOF tests is the model fit. R as a free software package has many GOF tests in different packages. A Monte Carlo simulation has been conducted to study two situations; the first, studying the ability of each test, under its default settings, to accept the null hypothesis when the model truly fitted. The second, studying the power of these tests when assumptions of sufficient linear combination of the explanatory variables are violated (by omitting linear covariate term, quadratic term, or interaction term). Moreover, checking whether the same test in different R packages had the same results or not. As the sample size supposed to affect simulation results, so the pattern of change of GOF tests results under different sample sizes as well as different model settings was estimated. All tests accept the null hypothesis (more than 95% of simulation trials) when the model truly fitted except modified Hosmer-Lemeshow test in "LogisticDx" package under all different model settings and Osius and Rojek’s (OsRo) test when the true model had an interaction term between binary and categorical covariates. In addition, le Cessie-van Houwelingen-Copas-Hosmer unweighted sum of squares (CHCH) test gave unexpected different results under different packages. Concerning the power study, all tests had a very low power when a departure of missing covariate existed. Generally, stukel’s test (package ’LogisticDX) and CHCH test (package "RMS") reached a power in detecting a missing quadratic term greater than 80% under lower sample size while OsRo test (package ’LogisticDX’) was better in detecting missing interaction term. Beside the simulation study, we evaluated the performance of GOF tests using the breast cancer dataset.

scholarly journals Role of Cooperative Societies in Boosting Agricultural Production & Entrepreneurship in the Kebbi State of Nigeria.

2017 ◽  
pp. 234-351
Author(s):  
Kamelshewer Lohana Et al.,
Keyword(s):  
Local Government ◽  
Sample Size ◽  
Agricultural Production ◽  
Null Hypothesis ◽  
Food Production ◽  
Sampling Technique ◽  
Added Value ◽  
Cluster Sampling ◽  
Survey Results

The study Assess the Role & contributions of cooperative societies in boosting agricultural production & Entrepreneurship in the Kebbi State of Nigeria. A total of 120 sample size was used for the study. Cluster sampling technique was used to obtaining information from sample respondents (members of farmers’ cooperative societies). Sixty (60) questionnaires were administered to sixty respondents, each in both Zuru and Yauri Local Government Areas. Data collected was analysed and interpreted using simple percentage and descriptive methods. The major conclusions drawn from this research were: survey results, regarding effectiveness of cooperative societies in improving agricultural production & Entrepreneurship, have shown that 33.3% and 25% of the respondents in Zuru and Yauri Local Government Areas reported promoting farmers’ participation in agriculture, while 25% and 46% agreed to boost agricultural production in the study areas. About 36.6% and 35% believed in the effectiveness of cooperative societies in increasing food production. Sample respondents in the two Local Government Areas 5% and 3.3% reported all of the above indicators increase the effectiveness of cooperatives to agriculture. Survey results regarding the role of cooperatives in boosting Entrepreneurship in the study areas shows that 75% Zuru 88.3% Yauri agreed that cooperatives have added value to boosting Agric production & Entrepreneurship and only 15% and 11.6% did not agree with the above opinion. Many problems were identified that affects the smooth functioning of cooperatives and solutions for addressing the problems were recommended. Therefore it was concluded that Null Hypothesis HO is rejected and Alternate Hypothesis HA is accepted.

Test procedure and sample size determination for a proportion study using a double-sampling scheme with two fallible classifiers

2017 ◽  
Vol 28 (4) ◽  
pp. 1019-1043 ◽  
Author(s):  
Shi-Fang Qiu ◽  
Xiao-Song Zeng ◽  
Man-Lai Tang ◽  
Wai-Yin Poon
Keyword(s):  
Sample Size ◽  
Null Hypothesis ◽  
Test Procedure ◽  
Sample Size Determination ◽  
Double Sampling ◽  
Score Statistic ◽  
Wald Statistic ◽  
Test Procedures ◽  
Practical Applications ◽  
Logit Transformation

Double sampling is usually applied to collect necessary information for situations in which an infallible classifier is available for validating a subset of the sample that has already been classified by a fallible classifier. Inference procedures have previously been developed based on the partially validated data obtained by the double-sampling process. However, it could happen in practice that such infallible classifier or gold standard does not exist. In this article, we consider the case in which both classifiers are fallible and propose asymptotic and approximate unconditional test procedures based on six test statistics for a population proportion and five approximate sample size formulas based on the recommended test procedures under two models. Our results suggest that both asymptotic and approximate unconditional procedures based on the score statistic perform satisfactorily for small to large sample sizes and are highly recommended. When sample size is moderate or large, asymptotic procedures based on the Wald statistic with the variance being estimated under the null hypothesis, likelihood rate statistic, log- and logit-transformation statistics based on both models generally perform well and are hence recommended. The approximate unconditional procedures based on the log-transformation statistic under Model I, Wald statistic with the variance being estimated under the null hypothesis, log- and logit-transformation statistics under Model II are recommended when sample size is small. In general, sample size formulae based on the Wald statistic with the variance being estimated under the null hypothesis, likelihood rate statistic and score statistic are recommended in practical applications. The applicability of the proposed methods is illustrated by a real-data example.

Null Hypothesis Significance Testing: Ramifications, Ruminations and Recommendations

2005 ◽  
Vol 35 (1) ◽  
pp. 1-20 ◽  
Author(s):  
G. K. Huysamen
Keyword(s):  
Sample Size ◽  
Confidence Intervals ◽  
Effect Size ◽  
Null Hypothesis ◽  
Significance Testing ◽  
Population Parameter ◽  
Size Estimation ◽  
Null Hypothesis Significance Testing ◽  
Point Estimates ◽  
Size Estimates

Criticisms of traditional null hypothesis significance testing (NHST) became more pronounced during the 1960s and reached a climax during the past decade. Among others, NHST says nothing about the size of the population parameter of interest and its result is influenced by sample size. Estimation of confidence intervals around point estimates of the relevant parameters, model fitting and Bayesian statistics represent some major departures from conventional NHST. Testing non-nil null hypotheses, determining optimal sample size to uncover only substantively meaningful effect sizes and reporting effect-size estimates may be regarded as minor extensions of NHST. Although there seems to be growing support for the estimation of confidence intervals around point estimates of the relevant parameters, it is unlikely that NHST-based procedures will disappear in the near future. In the meantime, it is widely accepted that effect-size estimates should be reported as a mandatory adjunct to conventional NHST results.

Correlation Between Vocabulary Mastery and Fluency in Speaking at Universitas Tanjungpura

2021 ◽  
Vol 10 (1) ◽  
pp. 36
Author(s):  
Diyas Herdian Putra ◽  
Ikhsanudin Ikhsanudin ◽  
Eusabinus Bunau
Keyword(s):  
Data Analysis ◽  
Sample Size ◽  
Null Hypothesis ◽  
English Education ◽  
Alternative Hypothesis ◽  
Study Program ◽  
Training And Education ◽  
Education Study ◽  
R Value ◽  
Level Of Significance

This research, entitled “Correlation Between Vocabulary Mastery and Fluency in Speaking” was carried out to the fifth semester students of English Education Study Program. The population of this research is fifth semester students of English Education Study Program of Teacher Training and Education Faculty at Tanjungpura University with the sample size of 30. The result of data analysis revealed the correlational between both variable from the samples is showing the correlational coefficient (r) value of 0.19. This value showed vocabulary mastery has low correlation with fluency in speaking. The contribution of vocabulary mastery to fluency in speaking is 3.6% which is almost non-existent. The hypothesis was tested by comparing the r value with r table, with the degree of freedom (df = n-2) of 28 and 1% level of significance. The r value (0.19) is lower than r table (0.463). It means, the alternative hypothesis (Ha) is rejected and null hypothesis (Ho) is accepted. With this research done, students should improve their speaking ability and remember more vocabularies to become a more and better speaker. The writer hopes this research may be beneficial to the readers and might resulting in newer research with different aspect and better concepts.

The null-hypothesis significance-test procedure is still warranted

1998 ◽  
Vol 21 (2) ◽  
pp. 228-235 ◽  
Author(s):  
Siu L. Chow
Keyword(s):  
Null Hypothesis ◽  
Statistical Power ◽  
Meta Analysis ◽  
Statistical Significance ◽  
Test Procedure ◽  
Significance Test ◽  
Null Hypothesis Significance Test ◽  
Wide Range ◽  
Statistical Hypotheses ◽  
Alternative Hypotheses

Entertaining diverse assumptions about empirical research, commentators give a wide range of verdicts on the NHSTP defence in Statistical significance. The null-hypothesis significance-test procedure (NHSTP) is defended in a framework in which deductive and inductive rules are deployed in theory corroboration in the spirit of Popper's Conjectures and refutations (1968b). The defensible hypothetico-deductive structure of the framework is used to make explicit the distinctions between (1) substantive and statistical hypotheses, (2) statistical alternative and conceptual alternative hypotheses, and (3) making statistical decisions and drawing theoretical conclusions. These distinctions make it easier to show that (1) H0 can be true, (2) the effect size is irrelevant to theory corroboration, and (3) “strong” hypotheses make no difference to NHSTP. Reservations about statistical power, meta-analysis, and the Bayesian approach are still warranted.

Comparing Training Techniques in Personal Protective Equipment Use

2020 ◽  
Vol 35 (4) ◽  
pp. 364-371 ◽  
Author(s):  
Richard J. Salway ◽  
Trenika Williams ◽  
Camilo Londono ◽  
Patricia Roblin ◽  
Kristi Koenig ◽  
...  
Keyword(s):  
Sample Size ◽  
Personal Protective Equipment ◽  
Emergency Preparedness ◽  
Null Hypothesis ◽  
Small Sample ◽  
Protective Equipment ◽  
Video Training ◽  
Significant Difference ◽  
Demonstration Video ◽  
Training Modalities

AbstractIntroduction:Physicians’ management of hazardous material (HAZMAT) incidents requires personal protective equipment (PPE) utilization to ensure the safety of victims, facilities, and providers; therefore, providing effective and accessible training in its use is crucial. While an emphasis has been placed on the importance of PPE, there is debate about the most effective training methods. Circumstances may not allow for a traditional in-person demonstration; an accessible video training may provide a useful alternative.Hypothesis:Video training of Emergency Medicine (EM) residents in the donning and doffing of Level C PPE is more effective than in-person training.Null Hypothesis:Video training of EM residents in the donning and doffing of Level C PPE is equally effective compared with in-person training.Methods:A randomized, controlled pilot trial was performed with 20 EM residents as part of their annual Emergency Preparedness training. Residents were divided into four groups, with Group 1 and Group 2 viewing a demonstration video developed by the Emergency Preparedness Team (EPT) and Group 3 and Group 4 receiving the standard in-person demonstration training by an EPT member. The groups then separately performed a donning and doffing simulation while blinded evaluators assessed critical tasks utilizing a prepared evaluation tool. At the drill’s conclusion, all participants also completed a self-evaluation survey about their subjective interpretations of their respective trainings.Results:Both video and in-person training modalities showed significant overall improvement in participants’ confidence in doffing and donning PPE equipment (P <.05). However, no statistically significant difference was found in the number of failed critical tasks in donning or doffing between the training modalities (P >.05). Based on these results, the null hypothesis cannot be rejected. However, these results were limited by the small sample size and the study was not sufficiently powered to show a difference between training modalities.Conclusion:In this pilot study, video and in-person training were equally effective in training for donning and doffing Level C PPE, with similar error rates in both modalities. Further research into this subject with an appropriately powered study is warranted to determine whether this equivalence persists using a larger sample size.

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