Significant Average Effect Research Articles

Geopolitics and the effect of foreign aid on economic growth: 1970–2001

AbstractPrevious aid effectiveness research often claims that foreign aid has been unsuccessful in increasing growth rates. This result could be due either to methodological weaknesses, or to genuine aid efficiency losses. Empirically, the author finds that once the best available techniques are employed, aid has a significant but moderate average effect on growth over the period 1970–2001. A promising explanation of why the estimated returns to aid are not larger is that bilateral aid had no significant effect on growth during the Cold War (pre‐1990), but had a significant and sizeable effect thereafter. In contrast, multilateral aid seems to have had sizeable and significant effects throughout. These results imply that the negative conclusions drawn by earlier research should be interpreted in their proper historical context, rather than as a necessary condemnation of current aid effectiveness. Copyright © 2007 John Wiley & Sons, Ltd.

Provincial Effects on Reading Achievement

Although Canadian students performed well on the 2000 Programme for International Student Assessment (PISA), there were considerable differences among provinces. Based on the Canadian sample of PISA 2000, our multilevel analysis examined the extent to which schools in various provinces produced differential effects on the reading achievement of their students. School characteristics that showed significant provincial effects on reading achievement included variables that described school context, school resources, and school climate, with most of these significant school-level variables being measures of school climate. Disciplinary climate and sense of belonging to school were the most important of significant school characteristics. They showed significant average effects by province on reading achievement, and their effects varied significantly across provinces. Results of our analysis suggest that provinces can use school effects to promote the reading achievement of their students.

Sexual Assault Education Programs: A Meta-Analytic Examination of Their Effectiveness

Meta-analyses of the effectiveness of college sexual assault education programs on seven outcome measure categories were conducted using 69 studies that involved 102 treatment interventions and 18,172 participants. Five of the outcome categories had significant average effect sizes (i.e., rape attitudes, rape-related attitudes, rape knowledge, behavioral intent, and incidence of sexual assault), while the outcome areas of rape empathy and rape awareness behaviors did not have average effect sizes that differed from zero. A significant finding of this study is that longer interventions are more effective than brief interventions in altering both rape attitudes and rape-related attitudes. Moderator analyses also suggest that the content of programming, type of presenter, gender of the audience, and type of audience may also be associated with greater program effectiveness. Implications for research and practice are discussed.

A Meta-Analytic Review of Gender Variations in Children's Language Use: Talkativeness, Affiliative Speech, and Assertive Speech.

Three sets of meta-analyses examined gender effects on children's language use. Each set of analyses considered an aspect of speech that is considered to be gender typed: talkativeness, affiliative speech, and assertive speech. Statistically significant average effect sizes were obtained with all three language constructs. On average, girls were slightly more talkative and used more affiliative speech than did boys, whereas boys used more assertive speech than did girls. However, the average effect sizes were either negligible (talkativeness, d=0.11; assertive speech, d=0.11) or small (affiliative speech, d=0.26). Larger effect sizes were indicated for some language constructs depending on either the operational definition of the language measure, the method of recording, the child's age level, the interaction partner (adult or peer), group size, gender composition, observational setting, or type of activity. The results are interpreted in relation to social-developmental and social-constructionist approaches to gender; these views are presented as complementary--rather than competing--meta-theoretical viewpoints.

Sedation and performance impairment of diphenhydramine and second-generation antihistamines: A meta-analysis

Background: Antihistamines are among the most frequently used medications in the United States. Despite dramatically higher cost, second-generation antihistamines are replacing diphenhydramine because of the perception that they are not constrained by its sedating effects. Objective: We sought to examine, through meta-analytic procedures, the collective evidence regarding the sedating and performance-impairing effects of diphenhydramine relative to placebo and second-generation antihistamines. Methods: A search that began with the MEDLINE database was limited to those studies that included patients with atopic disease and control subjects, were blinded and randomized clinical trials, objectively examined alertness and psychomotor performance, reported means and variances, and were written in English. Information was systematically abstracted from the resulting 18 articles, and effect size was calculated. Results: Diphenhydramine impaired performance relative to placebo control and second-generation antihistamines, including acrivastine, astemizole, cetirizine, fexofenadine, loratadine, and terfenadine. However, results were quite varied, the average sedating effect of diphenhydramine was modest, and in some instances results of tests of performance in the diphenhydramine group showed less sedation than in the control or second-generation antihistamine groups. A significant ( P < .05) average effect size indicated a mild sedating effect caused by second-generation antihistamines in comparison with placebo. Conclusion: The absence of a consistent finding of diphenhydramine-induced sedation is surprising given that most studies have been designed to increase the probability of this outcome, including administering a 50-mg dose. On the basis of this meta-analysis of performance-impairment trials, a clear and consistent distinction between sedating and nonsedating antihistamines does not exist.

BEHAVIORAL MANAGEMENT AND TASK PERFORMANCE IN ORGANIZATIONS: CONCEPTUAL BACKGROUND, META‐ANALYSIS, AND TEST OF ALTERNATIVE MODELS

In this study, we provide the conceptual background, meta‐analyze available behavioral management studies (N= 72) in organizational settings, and examine whether combined reinforcement effects on task performance are additive (sum of individual effects), redundant (combined effects are less than the additive effects), or synergistic (combined effects are greater than the sum of the individual effects). We found a significant overall average effect size of (d.) = .47 (16% improvement in performance; 63% probability of success), and a significant within‐group heterogeneity of effect sizes. To account for this variation, we conducted a theory‐driven moderator analysis, which indicated that money, feedback, and social recognition each had a significant impact on task performance. However, when these 3 reinforcers were used in combination, they produced the strongest (synergistic) effect on task performance. Based on our findings, we offer directions for future research, and suggestions for effective application of behavioral management at work.

Preadolescent girls with attention-deficit/hyperactivity disorder: II. Neuropsychological performance in relation to subtypes and individual classification.

This study examined executive functions, motor speed, and language processing in a diverse, preadolescent sample of 93 girls with attention-deficit/hyperactivity disorder (ADHD) combined type, 47 ADHD inattentive type, and 88 age- and ethnicity-matched comparison girls. Testing was performed without stimulant medication. All 10 neuropsychological variables showed significant omnibus subgroup differences, with 8 of 10 combined versus comparison contrasts significant (average effect size medium) and 6 of 10 inattentive versus comparison contrasts significant (average effect size small to medium), but only 2 of 10 combined versus inattentive contrasts significant (average effect size small). Results were robust to statistical control of demographic variables, comorbidities, and IQ. Discriminant function analysis revealed relatively high sensitivity but only modest specificity in predicting ADHD from comparison status from test performance; classification of the inattentive type was extremely poor.

Low insulin resistance and preserved β-cell function contribute to human longevity but are not associated with TH–INS genes

Tyrosine Hydroxylase (TH) and Insulin (INS) genes lie extremely close in the 11p15.5 chromosomal region. An STR marker of the TH gene had revealed this locus associated with longevity. Thus, it seemed of interest to investigate the association between the TH-STR and INS gene variability (FokI-RFLP) with a phenotypic trait, such as the degree of insulin resistance (IR) and β-cell function in centenarians (C). We analyzed age-related trajectories of IR and β-cell function in a large sample ( n=466) of individuals whose age ranged from 28 to more than 100 years; furthermore, allele average effects on IR and β-cell function relevant to TH-STR and INS-FokI polymorphisms were estimated in C. Both IR and β-cell function increased with advancing age and declined in subjects older than 90 years ( p for trend <0.001). C had lower IR (1.5±0.7 vs 3.9±1.7, p<0.001) and β-cell function (26.1±8.5 vs 55.4±16, p<0.001) than nC. In nC, but not in C, IR and β-cell function correlated with the main anthropometric and metabolic confounders. Nevertheless, significant allele average effects by TH-STR and INS-FokI polymorphisms on IR and β-cell function were not observed in C. In conclusion, C has a lower degree of IR and a preserved β-cell function in comparison to nC, but the cause of such metabolic differences, which are likely does not lie in this genomic region.

Genetic control of some polymeric glutenin fractions in hexaploid wheat (Triticum aestivum)

AbstractReciprocal crosses were made between seven different hexaploid wheat genotypes. Hybrid kernels and their parents were used to determine the amount of polymeric glutenin fractions by size‐exclusion high‐performance liquid chromotography (SE‐HPLC) analysis. Quantitative aspects of the genetic control for various glutenin fractions were investigated through diallel cross analysis. The association between the potential effect on hexaploid wheat quality of various allelic types and the quantitative expression of the polymeric glutenin fractions was confirmed. Significant average heterosis effects were demonstrated for insoluble glutenin (pFi), total soluble and insoluble glutenin (pF1 + pF2 + pFi) and the ratio of soluble to insoluble glutenin, (pF1 + pF2)/pFi. Some genotypes showed significant positive or negative combining abilities and general reciprocal effects for the glutenin fractions studied. For gluten quality, ‘Qualital’ was the best combiner for determining an optimal glutenin composition (high values for pFi and pF1 + pF2 + pFi and low values for pF1/pF2 and (pF1 + pF2)/pFi, respectively). These results should be of great interest in breeding programmes aimed at improving hexaploid wheat quality.

Reaction norm variation in a rare plant, Senecio integrifolius (Asteraceae)

This study examines the pattern of reaction norm variation and the extent to which genetic constraints could prevent the evolution of broader ecological tolerance in Senecio integrifolius, a rare and declining plant in Sweden. Following the establishment of biparental progenies, we planted seedlings from each full-sib family in two greenhouse environments: full daylight and 50 per cent shade. A 2-year demographic study indicated that full-sib genotypes representing a large population at a site with a fine-scale mosaic habitat (meadow with clumps of shrubs) had a significantly greater overall performance across the environments and a lower sensitivity to a drastic reduction in light intensity than genotypes representing a small and patchily distributed population at a site without spatial variation (meadow exposed to full sun), confirming the supposition of more broadly adapted genotypes in a large population subject to selection across a wider range of micro-habitats. There was a significant average effect of genotype for all traits but we failed to detect within-population variation in phenotypic response (G × E) for direct components of fitness and conclude that there is little potential for specialization to particular light regimes. Across-environment correlations using full-sib means were small and positive and there was no change in the ranking of population means across the two environments, implying a lack of strong trade-offs within the reaction norm. However, the changes in ecological amplitude may not be of sufficient magnitude to permit long-term survival of remaining populations, as implied by the rapid decline of S. integrifolius in Sweden.

Making the Gift Horse Jump the Hurdles: The Impact of the TVEI Pilot on the first Scottish Cohort

Abstract TVEI in its pilot phase seeks to ‘test and explore’ new approaches to the education and training of 14‐18 year‐olds. Quantitative performance indicators can be used to assess its impact in two ways. ‘Whole‐school’ comparisons contrast the performance of TVEI schools with other schools nationally, and with their own performance in earlier years. ‘Within‐school’ comparisons contrast TVEI with non‐TVEI students from the same schools. Whole‐school comparisons, based on the year group which included the first Scottish pilot TVEI cohort, found no impact of TVEI on examination attainment, truancy, staying‐on at 16 or the employment of early leavers. Within‐school comparisons found a favourable (if problematic) effect on truancy, but found no significant average effect across the Scottish projects on the other outcomes. However the effects of TVEI on all outcomes varied across schools or projects. The true test of the success of the TVEI pilot is its ability to learn from this variation, and will be meas...

Convertible debt issuance, capital structure change and financing-related information

This paper provides evidence on the valuation effects of convertible debt issuance. Common stockholders earn significant negative abnormal returns at the initial announcement of a convertible debt offering, and also at the issuance date. In contrast, the average valuation effect on common stock at the announcement of non-convertible debt offerings is only marginally negative, and is zero at issuance. The significant negative average effect on common stock value appears not to be systematically related to either the degree of leverage change induced by the convertible debt issuance or the extent to which the proceeds from issuance are used for new investment or to refinance existing debt. If, as appears likely, the issuance of convertible debt on average increases financial leverage, these results are inconsistent with evidence from other recent studies documenting common stock price effects of the same sign as the change in leverage. The evidence suggests that convertible debt offerings convey unfavorable information about the issuing firms, but the specific nature of such information remains unidentified.

Standstill agreements, privately negotiated stock repurchases, and the market for corporate control

Abstract Standstill agreements are voluntary contracts which limit a substantial stockholder's ownership interest in a corporation for a specified number of years. They are often accompanied by repurchase of the substantial stockholder's shares at a premium above the market price. Standstills and premium buybacks reduce competition for corporate control and provide differential treatment of large block stockholders. The analysis indicates a statistically significant negative average effect on non-participating stockholder wealth associated with standstill agreements. Negotiated premium repurchases are also associated with negative, but less significant, stockholder returns. The evidence is inconsistent with the hypothesis that these management actions are in the best interests of non-participating stockholders.

Examination of the filterability of oxygenated erythrocytes (containing normal, trait or sickle cell disease type hemoglobins) in the presence of [formula omitted]-epinephrine, [formula omitted]-isoproterenol or prostaglandins (PG) A 1, A 2, E 1, E 2, F 1α or F 2α

These studies were directed toward determining effects of selected vasoactive compounds on oxygenated erythrocytes. Considering the major circulatory effects that small changes in blood flow might initiate in sickle cell anemia patients, erythrocytes from individuals with this disease and from one person with the trait condition were included. PGA 1, PGE 1, and PGE 2 significantly increase filtration times in normal erythrocytes (AA-type hemoglobin) at 10 −11 M by this method. From studies of the effects of L -epinephrine, D,L -isoproterenol, PGA 1, PGA 2, PGE 1, PGE 2, PGF 1α and PGF 2α on red blood cell filterabilities, the following observations and conclusions appear to hold: 1. Erythrocytes from different individuals (or from the same individual at different times) vary greatly in responses to these compounds. Effects of vasoactive compounds upon red cell filterability may be positive, negligible or negative. Decreased filterability (positive effect) was seen more frequently than increased. 2. Effects are observed with all compounds on some erythrocyte preparation at every concentration tested (10 −5, 10 −7, 10 −9, 10 −11 M). 3. Where epinephrine showed significant positive effect, PGA 2 and PGE 2 did also when tested. The reverse was not always true. 4. For PGA and PGE analogs, the subscript 2 analogs affected filterability more frequently. 5. When significant average effects for a group of donors were produced by a given compound at a particular concentration, these effects were positive for the donors studied.

The death of micro-organisms during drying in relation to solute concentration and drying temperature.

SUMMARY: A mixture of Pseudomonas fluorescens and coliphage T2 was dried at − 20, 0 and + 20° in solutions of each of the 16 combinations of mannitol and sucrose at 0, 0·25, 0·50, and 0·75 m. For P. fluorescens there was no significant average effect of the drying temperature on the numbers which survived drying, but for coliphage T2 average survival increased as the drying temperature was changed from − 20 to 20°. For both organisms, however, there were a number of very highly significant interactions between solutions and drying temperatures. In other words, the effects of the temperature depended on the solutes present and vice versa. There were also some substantial differences between the responses of the two organisms. It is concluded that survival during drying is likely to be determined by factors additional to those studied in these experiments.