High Level Of Statistical Significance Research Articles

Estimation of the lipophilic character of flavonoids from the retention behavior in reversed phase liquid chromatography on different stationary phases: A comparative study

The retention behavior of some flavonoids in reversed phase liquid chromatography (RPLC) was investigated using different chemistries of the modified silicagel based stationary phases. Highly end-capped octadecyl silicagel (ODS), polar embedded linker octadecyl silicagel (SB-18 Aqua), phenyl silicagel and pentafluorophenyl modified silicagel (PFP) were used as stationary phases. The mobile phase consisted in acetonitrile/acidified water mixtures, at different fractions of volume. The lipophilicity was estimated through different chromatographic descriptors, as it follows: log k w , m log k, S, φ 0 and PC1/log k. The chromatographic behavior observed on the mentioned stationary phases was evaluated by means of various graphical profiles and correlation matrices. Additionally, new information about the characteristics of the stationary phases and their (dis)-similarities were provided through lipophilicity charts and by scatterplots of loadings obtained by applying principal component analysis (PCA) to retention data. Furthermore, the experimental lipophilicity indices estimated from retention data were correlated with the computed descriptors, at a high level of statistical significance.

Development of the Environmental Strategies Instrument to Measure Adolescent Alcohol Prevention–Related Outcomes in Community Settings

Recently, evidence-based community policy approaches to preventing substance use and alcohol abuse, called environmental strategies, have gained in popularity. The environmental survey instrument (ESI) was developed to evaluate perceptions around drinking and related problems. Specifically, the authors were interested in assessing community perceptions about prevention practices. The 53-item self-report survey tool collects data on alcohol consumption patterns and risky behaviors such as drinking-while-intoxicated (DWI) rates. Data from the ESI collected through phone survey methods in 2008 were used for scale development analysis. The α for the total 53 subscale items on the ESI was .73. Overall, the results from the correlation matrix showed high levels of statistical significance with many items reporting p values less than .001. Additionally, an exploratory factor analysis (EFA) was conducted to examine the conceptual linkage across items in the instrument subscales. The EFA showed a link between previously theorized intervening variables and statistically derived factors. The results of the ESI study were encouraging, and findings from it can help inform future research on measurement of environmental strategies.

HAT-P-27b: A HOT JUPITER TRANSITING A G STAR ON A 3 DAY ORBIT

We report the discovery of HAT-P-27b, an exoplanet transiting the moderately bright G8 dwarf star GSC 0333-00351 (V=12.214). The orbital period is 3.039586 +/- 0.000012 d, the reference epoch of transit is 2455186.01879 +/- 0.00054 (BJD), and the transit duration is 0.0705 +/- 0.0019 d. The host star with its effective temperature 5300 +/- 90 K is somewhat cooler than the Sun, and is more metal-rich with a metallicity of +0.29 +/- 0.10. Its mass is 0.94 +/- 0.04 Msun and radius is 0.90 +/- 0.04 Rsun. For the planetary companion we determine a mass of 0.660 +/- 0.033 MJ and radius of 1.038 +0.077 -0.058 RJ. For the 30 known transiting exoplanets between 0.3 MJ and 0.8 MJ, a negative correlation between host star metallicity and planetary radius, and an additional dependence of planetary radius on equilibrium temperature are confirmed at a high level of statistical significance.

Demographic Changes, Financial Markets, and the Economy

It seems natural that the shifting composition of a nation’s population ought to influence GDP growth and perhaps also capital markets returns. As the baby boomers have aged, many people have studied past demographic data in an effort to extract indications for the future influence of the boomers on many aspects of the economy. We extend this body of literature by analyzing the effect of demographic changes on three measures of great importance for countries all over the world: real per capital PPP-adjusted GDP growth, stock market excess returns, and bond market excess returns. We confirm what others have already demonstrated, but we extract markedly more statistical significance by adapting a polynomial curve-fitting technique pioneered by Fair and Dominguez (1991), to this new purpose. In our work, we find that a growing roster of young adults (age 15–49) is very good for GDP growth, a growing roster of older workers is a little bad for GDP growth, and a growing roster of young children or senior citizens is very bad for GDP growth. We find surprisingly powerful results when we apply the same technique for exploring the links between demography and capital markets returns, net of the strong and well-documented effects of valuation and yield levels. Stocks perform best when the roster of people age 35–59 is particularly large, and when the roster of people age 45–64 is fast-growing. Bonds follow a similar pattern, with an age-shift: they’re best when the roster of people age 50–69 is growing quickly. We carry out three different forms of robustness checks, each of which provides statistical significance in different ways: applying different country weights, testing alternative demographic variables, and confirming GDP results on out-of-sample countries. It would be dangerous to forecast the future based on these results. Tacitly, we would be assuming that past relationships between demography and either GDP growth or capital market returns will hold unaltered in the future. However, given the high levels of statistical significance in the historical relationships, it is too tempting to resist exploring the possible implications for future GDP growth and capital market returns. These implications—with all the caveats that must necessarily be offered—are sobering, to say the least.

TRPC5 Channel Sensitivities to Antioxidants and Hydroxylated Stilbenes

Transient receptor potential canonical 5 (TRPC5) forms cationic channels that are polymodal sensors of factors including oxidized phospholipids, hydrogen peroxide, and reduced thioredoxin. The aim of this study was to expand knowledge of the chemical-sensing capabilities of TRPC5 by investigating dietary antioxidants. Human TRPC5 channels were expressed in HEK 293 cells and studied by patch clamp and intracellular Ca2+ recording. GFP- and HA-tagged channels were used to quantify plasma membrane localization. Gallic acid and vitamin C suppressed TRPC5 activity if it was evoked by exogenous hydrogen peroxide or lanthanide ions but not by lysophosphatidylcholine or carbachol. Catalase mimicked the effects, suggesting that lanthanide-evoked activity depended on endogenous hydrogen peroxide. Trans-resveratrol, by contrast, inhibited all modes of TRPC5, and its effect was additive with that of vitamin C, suggesting antioxidant-independent action. The IC50 was ∼10 μm. Diethylstilbestrol, a related hydroxylated stilbene, inhibited TRPC5 with a similar IC50, but its action contrasted sharply with that of resveratrol in outside-out membrane patches where diethylstilbestrol caused strong and reversible inhibition and resveratrol had no effect, suggesting indirect modulation by resveratrol. Resveratrol did not affect channel surface density, but its effect was calcium-sensitive, indicating an action via a calcium-dependent intermediate. The data suggest previously unrecognized chemical-sensing properties of TRPC5 through multiple mechanisms: (i) inhibition by scavengers of reactive oxygen species because a mode of TRPC5 activity depends on endogenous hydrogen peroxide; (ii) direct channel blockade by diethylstilbestrol; and (iii) indirect, antioxidant-independent inhibition by resveratrol.

Comment on “Coastal Caves in Bahamian Eolian Calcarenites: Differentiating between Sea Caves and Flank Margin Caves using Quantitative Morphology”

Waterstrat et al. (JCKS (2010), 72 (2) 61–74) calculated means of various geometric properties of collections of sea caves and flank-margin caves with the professed aim of showing that they can be statistically distinguished. If this is meant to be useful for determining whether a given coastal cave is one sort or the other, the results are useless, because the standard deviations of the distributions are larger than the differences in the means—a fancy way of saying that the distributions overlap substantially. If the intention of the paper is to show that the two types of caves differ in the various properties to a statistically significant extent, it is hardly noteworthy. Statistical tests such as Student’s t are useful in cases where the natural assumption is that there is no difference between two classes, a typical example being whether a new drug is more effective than an old one. In the case of caves, I can state with full confidence that any sufficiently large collections of caves formed by different mechanisms, or indeed by the same mechanism in different geological environments, will differ significantly in shape, however that is defined. Indeed, the authors point out various qualitative features that can be used to differentiate flankmargin caves from sea caves. When anyone familiar with coastal caves can usually tell from a glance at its map which category a cave belongs to, it is not surprising that extremely high levels of statistical significance can be reached, limited only by the number of data points available. One of the parameters investigated by the authors is not even dimensionless. Given two collections of caves that match one-to-one in shape exactly, but with one collection being systematically 1% longer than the other, their mean ratios of perimeter to area will differ to any level of significance you like, given large enough samples. B. Mixon – Comment on ‘‘Coastal Caves in Bahamian Eolian Calcarenites: Differentiating Between Sea Caves and Flank Margin Caves Using Quantitative Morphology’’. Journal of Cave and Karst Studies, v. 73, no. 3, p. 202. DOI: 10.4311/jcks2011es0195

Polymorphisms in DNA repair genes and risk of non-Hodgkin lymphoma in a pooled analysis of three studies

Genetic variations in DNA repair genes are thought to play an important role in the pathogenesis and development of non-Hodgkin lymphoma (NHL). To further explore this hypothesis, we genotyped 319 tag single nucleotide polymorphisms (SNPs) in 27 DNA repair gene regions in 1946 cases and 1808 controls pooled from three population-based case-control studies of NHL in the US and Australia. Relative risks of NHL and NHL subtypes in relation to SNP genotypes were assessed using logistic regression. Associations of gene regions and pathways with NHL or NHL subtypes were explored using the minP and tail-strength statistics, respectively. Overall, genetic polymorphisms within the DNA repair pathway were associated with NHL (P = 0·005). Similar associations were seen with the double-strand break repair (P = 0·02) and nucleotide excision repair (P = 0·04) pathways. Five SNPs (BLM rs441399, RAD50 rs2237060, FAM82A2 rs2304583, ERCC3 rs4150506, and XRCC4 rs13178127) were particularly noteworthy because their gene regions were significantly associated with NHL or NHL subtypes (minP ≤ 0·05), or because of high level of statistical significance (P ≤ 0·005) and consistent findings across the three studies. These results support the hypothesis that common genetic polymorphisms in human DNA repair genes may modify the risk of NHL.

Opacity, Crash Risk, and the Option Smirk Curve

We investigate three facets of cross-sectional variation in the risk of stock price crashes: actual crash incidence, and two predictors of that risk, accounting opacity and the option smirk curve. We show that all three of these variables are related. Option smirks and accounting opacity each independently predict cross-sectional variation in crash risk and crash magnitude. The slope of the smirk curve and opacity are themselves correlated at extremely high levels of statistical significance, indicating that the market is aware of the link between opacity and crash risk. Nevertheless, even controlling for the option smirk, several measures of accounting opacity continue to be reliably associated with crash risk, suggesting that the options market does not fully utilize the predictive value of accounting opacity. Moreover, some of our results are consistent with behavioral models in which strong recent performance is extrapolated too far into the future, only to result in a major reversal when those expectations are disappointed.

Moderate Patient-Prosthesis Mismatch Has No Independent Effect on 30-Day Mortality After Isolated Aortic Valve Replacement

It is still not clear whether the presence of a moderate patient-prosthesis mismatch after isolated aortic valve replacement can increase 30-day mortality. The aim of this study was to determine whether a moderate mismatch is an independent predictor of early global or cardiac mortality after aortic valve replacement. The study involved 272 adult patients (median age, 72 years; interquartile range, 66-76 years) undergoing isolated aortic valve replacement. Moderate mismatch was considered to be present if the projected indexed effective orifice area was < or =0.85 and >0.65 cm2/m2. Severe mismatch was present if the projected indexed effective orifice area was < or =0.65 cm2/m2. Follow-up to assess survival at 30 days was carried out in 100% of patients. Moderate mismatch was observed in 37.9% of patients. None had a severe mismatch. Multivariate analysis identified the following independent predictors of global mortality at 30 days: left ventricular ejection fraction <50% (P=.03) and age (P=.01). The same variables were identified as predictors of 30-day cardiac survival, but at a higher level of statistical significance: left ventricular ejection fraction <50% (P=.006) and age (P=.008). The analysis did not identify moderate mismatch as a predictor of global or cardiac 30-day mortality in our study population. Our findings indicate that the evidence that inserting a prosthesis of the measured size in a small aortic annulus compromises the patient's survival is far from clear when the patient-prosthesis mismatch is moderate.

Atmospheric CO 2 enrichment changes the wheat grain proteome

Spring wheat ( Triticum aestivum L. cv. Triso) was grown in a free-air CO 2 enrichment (FACE) field experiment in order to gain information on CO 2-induced effects on grain composition and quality at maturity. A proteome analysis was performed using two-dimensional gel electrophoresis (2-DE) and protein identification was done with mass spectrometry (MALDI-TOF MS). In elevated CO 2 (526 μl l −1), an increase of 13.5% in grain yield was observed relative to 375 μl l −1 at a low level of significance ( P = 0.528). Total grain protein concentration was decreased by 3.5% at a high level of statistical significance. Most importantly, a number of statistically significant changes within the grain proteome were observed, as the levels of 32 proteins were affected by elevated CO 2: 16 proteins were up-regulated and 16 were down-regulated. Our experiment demonstrates that high-CO 2 can markedly affect the proteome of mature wheat grain. The potential role of the proteins, changed in response to CO 2 enrichment, is discussed as some may affect grain quality. For the task of selecting cultivars resistant to CO 2-induced quality loss, we propose to consider the proteins affected by elevated CO 2 identified in this work here.

How Markets Slowly Digest Changes in Supply and Demand

Publisher Summary This chapter discusses the new approach to the classic problem of tâtonnement —the dynamic process through which markets seek to reach equilibrium. The foundation of this approach is based on several empirical observations about financial markets. The most important of which is long memory in the fluctuations of supply and demand. This is exhibited in the placement of trading orders and corresponds to long-term, slowly decaying positive correlations in the initiation of buying versus selling. It is observed in all the stock markets studied so far at very high levels of statistical significance. It appears that the primary cause of this long memory is the incremental execution of large hidden trading orders. The fact that the long memory of order flow must coexist with market efficiency has a profound influence on price formation, causing dynamic adjustments of liquidity that are strongly asymmetric between buyers and sellers. This has important consequences for market impact. This work has also important consequences about the interpretation and effect of information in financial markets. In particular, the explanation for market impact is that the shape of the impact function is determined by differences in the information content of trades.

Comparison of Chinese and US orthodontists' averaged evaluations of “facial attractiveness” from end-of-treatment facial photographs

This study continues our assessment of agreement and disagreement among 25 Chinese and 20 US orthodontists in the ranking for facial attractiveness of end-of-treatment photographs of randomly sampled growing Chinese and white orthodontic patients. The main aims of this article were to (1) measure the overall pattern of agreement between the mean rankings of US and Chinese orthodontists, and (2) measure the strength of agreement between the rankings of the US and Chinese orthodontists for each patient. Each judge independently ranked standard clinical sets of profile, frontal, and frontal-smiling photographs of 43 US patients and 48 Chinese patients. For each patient, a separate mean rank was computed from the responses of each group of judges. Pearson correlations between the mean ranks of the 2 groups of judges were used to measure their overall agreement. Paired and unpaired t tests were used to measure the agreement between the judges of the 2 groups for each patient. The overall agreement between the mean rankings of the US and Chinese judges was very high. For the US patients, the correlation between the Chinese and US judges means was r = 0.92, P <0.0001. For the Chinese patients, the analogous value was r = 0.86, P <0.0001. Agreement between the 2 groups of judges concerning each patient was also generally strong. For two thirds of the patients, the mean ranks of the US and Chinese judges differed by less than 1 unit in a scale of 12. However, for 6 patients considered individually (5 Chinese and 1 US), the assessment of the 2 groups of judges was statistically significantly different at P values ranging from 0.02 to less than 0.0001, even after the Bonferroni correction. These findings demonstrate that orthodontic clinicians can reliably identify and rank subtle differences between patients, and that differences between judges and between patients can be distinguished at a high level of statistical significance, given appropriate study designs. However, the reasons clinicians give for the differences in their judgments are more difficult to investigate and will require further study.

An Experimental Study of Antecedents and Consequences of Online Ad Intrusiveness

Internet advertising has shown signs of continued healthy growth in spite of the burst Internet bubble. Several types of ads have been used, and there are important generic characteristics that can be gleaned from these ads: whether they obscure content and whether users have the control to remove them. These factors were tested in a laboratory study with 258 student participants. It was hypothesized that the factors would predict intrusiveness, which would predict perceived irritation. This, in turn, would predict attitudes about the site and, finally, intentions to return. Intrusiveness was also predicted to directly relate to recognition of the ads. All hypotheses were supported at high levels of statistical significance using analysis of variance and structural equation modeling. Explained variance was very high for intrusiveness (42%) and irritation (63%), but very low explained variance for ad recognition (11%) resulted in an alternative model that doubled explained variance by removing intrusiveness as a mediator between the factors and ad recognition. The interaction between user control and obscuring of the content behaved as hypothesized, and interaction charts illustrate the effects as predicted. Future studies should continue to focus on characteristics rather than on types of ads and generalize the results to other types of participants and settings.

Statistical Significance Versus Clinical Significance

Unfortunately, the data were statistically nonsignificant due to insufficient power and poor experimental design. Conversely, many large clinical trials obtain a high level of statistical significance with miniscule differences between groups, which are completely clinically irrelevant. However, with proper marketing, billions can be made from results of dubious clinical importance. In this article, the differences between statistical and clinical significance are briefly discussed.

The Sarbanes-Oxley act and the production efficiency of public accounting firms in supplying accounting auditing and consulting services: an application of data envelopment analysis

In this paper, we employ alternate techniques to examine whether passage of the Sarbanes-Oxley (SOX) Act has had positive effects on the efficiency of public accounting firms. These alternate techniques extend from use of the non-parametric, 'frontier'-oriented method of Data Envelopment Analysis (DEA), and include more traditional regression-based approaches using central tendency estimates. Using data from 58 of the 100 largest accounting firms in the USA, we find that efficiency increased at high levels of statistical significance and discover that this result is consistent for all of the different methods - frontier and central tendencies used in this paper. We also find that this result is not affected by inclusion or exclusion of the Big 4 firms. All results are found to be robust as well as consistent.

MMsat—a database of potential micro- and minisatellites

We present MMsat—a database of DNA sequences from GenBank possessing the latent periodicity at high level of statistical significance and having the period length in a range from 2 to 100 bases. The periodicity was found by analytical method of information decomposition. These sequences can be considered as potential micro- and minisatellites and thus can be useful for PCR analysis and evolutional studies. Distribution, properties, and potential functions of periodicity are discussed. Availability: http://victoria.biengi.ac.ru/mmsat

A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags

ABSTRACTWhile poleward species migration in response to recent climatic warming is widely documented, few studies have examined entire range responses of broadly distributed sessile organisms, including changes on both the trailing (equatorward) and the leading (poleward) range edges. From a detailed population census throughout the entire geographical range of Aloe dichotoma Masson, a long‐lived Namib Desert tree, together with data from repeat photographs, we present strong evidence that a developing range shift in this species is a ‘fingerprint’ of anthropogenic climate change. This is explained at a high level of statistical significance by population level impacts of observed regional warming and resulting water balance constraints. Generalized linear models suggest that greater mortalities and population declines in equatorward populations are virtually certainly the result, due to anthropogenic climate change, of the progressive exceedance of critical climate thresholds that are relatively closer to the species’ tolerance limits in equatorward sites. Equatorward population declines are also broadly consistent with bioclimatically modelled projections under anticipated anthropogenic climate change but, as yet, there is no evidence of poleward range expansion into the area predicted to become suitable in future, despite good evidence for positive population growth trends in poleward populations. This study is among the first to show a marked lag between trailing edge population extinction and leading edge range expansion in a species experiencing anthropogenic climate change impacts, a pattern likely to apply to most sessile and poorly dispersed organisms. This provides support for conservative assumptions of species’ migration rates when modelling climate change impacts for such species. Aloe dichotoma's response to climate change suggests that desert ecosystems may be more sensitive to climate change than previously suspected.

Assessing the Reliability of Blind Wine Tasting: Differentiating Levels of Clinical and Statistical Meaningfulness

AbstractThe author distinguishes between the clinical and statistical meaning of varying levels of intertaster reliability for the 11 judges who evaluated 10 Chardonnays (6 American and 4 French) in the heralded 1976 Paris wine competition. Four wines showed levels of weighted kappa values (&lt;0.40), that are considered poor by established biostatistical criteria. These ranged between 0.10, for the French Beaune Clos des Mouches 1973 Chardonnay to 0.33 for the U.S. Veedercrest 1972 Chardonnay. However, when levels of statistical significance of the weighted kappa (Kw) values were obtained, only the Clos des Mouches failed to reach statistical significance at the .05 level. The other three wines-the U.S. Chateau Montelena, 1973, with a Kwof 0.20; the U.S. 1973 David Bruce regular, with a weighted kappa value of .27 and the U.S. Veedercrest, with one of .33-reached statistical significance at p values of &lt;.05, &lt;.001, and &lt;.0001, respectively. These findings are not weighted kappa specific, and reveal that when sample sizes are large enough, even the most trivial of results will be statistically significant, while often devoid of practical or clinical meaning-fulness. A level of Kwthat is clinically meaningful will most likely be statistically significant. But high levels of statistical significance are no guarantee of clinical significance. Methods for resolving this “big N phenomenon” are presented and discussed. (JEL Classification: C12, C49)

Consumer Bankruptcy Filings: Trends and Indicators

This paper examines consumer bankruptcy filing rates. It attempts to identify some trends and some economic indicators that might predict those filing rates. While several studies examined these questions prior to the passage of the Bankruptcy Abuse Prevention and Consumer Protection Act of 2005 (BAPCPA), there remains considerable uncertainty and debate over what economic factors correlate to consumer bankruptcy. This is the first study that takes into account the impact of BAPCPA, both in anticipation of and in the aftermath of its effective date. 1. Part I lays out the historical filing rate data following the effective date of the Bankruptcy Reform Act of 1978. Part II examines the impact of BAPCPA on filing rates, and finds that the dramatic post-BAPCPA drop in filings may be almost over. Soon, consumer bankruptcy filing rates are likely to return to their pre-BAPCPA levels. Part III then analyzes the possible correlation of numerous plausible economic data sets to non-business bankruptcy filing rates. The paper finds several such data sets that correlate to non-business filings to a high level of statistical significance. These economic indicators point to a return to pre-BAPCPA filing levels. However, those indicators also suggest that it is unlikely that consumer filings will increase much over those old levels unless fundamental underlying economic changes occur. The findings in Part III further indicate that if Congress wants to curb consumer bankruptcy filings, it needs to focus on treating root causes - such as the explosion in revolving consumer credit - rather than on symptoms. Thus, BAPCPA may have been misguided

The Role of Transaction Costs for Financial Volatility: Evidence from the Paris Bourse

This paper analyzes the causal linkage between transaction costs and financial volatility under two methodological improvements over the existing literature. First, we use panel data in which exogenous transaction cost differences in the French stock market are induced by price level dependent minimum price variation rules (tick size rules). Unlike in previous studies based on one-time regulatory tick size changes (like the U.S. decimalization), we can separately identify and control for marketwide volatility changes. Second, we avoid the pitfalls of biased volatility measurement across regimes by using the range as a tick size robust volatility metric. Panel regressions controlling for marketwide volatility effects show at high levels of statistical significance that the hourly range volatility of individual stocks increases by more than 30% for a 20% exogenous increase in transaction costs due to tick size variations in the French trading system. In the light of this evidence, higher transaction costs in general, and security transaction taxes in particular, should be considered as volatility increasing. (JEL: F3, G1, G14)